Most of this stuff is well known to researchers, as acknowledged, and I don't think that finding IQ is only 40% or 50% heritable will make people's political hopes and aspirations that much more realistic. The remaining 50% or so is everything including the prenatal environment, any diseases or developmental irregularities, family environment, schools, friends, books people have read, etc. There's just much less room for social intervention to create equality than assumed in public policy debates, where nobody will say that rich kids are smarter than poor kids in part because of their genes.
A key point is that the replication crisis has shown that all research and research publications that were not pre-registered are suspect, especially in the field of academic psychology. Confirmation bias is a major factor in the conclusions researchers draw behind the scenes, and to be fair, this observation applies to "environmentalist" research as well. It's not like Cyril Burt was a bad apple in an otherwise healthy barrel of psychology research. The replication crisis shows us that a sizable portion of the barrel contained rotten apples that made it past peer review. That, by the way, is the only valid defense of Burt's "study" I can come up with.
How do you jump from emotions to ideology? That is a crazy interpretation of my perspective!
As is explained in this post (and many of my other posts), what is fundamentally at stake for me is that my mathematical career (and more specifically my ascension to a level that I had long thought I was biologically incapable of) made me rethink my entire perspective on language, logic, intuition, and cognition.
This is a very important topic, adjacent to the IQ debate, but of prime importance to many practitioners of mathematics—including the many Fields medals and Abel prizes who have read and praised my book.
The adjacency is this: it is very unlikely that math talent could be as malleable as I think it is (alongside Descartes, Einstein, Grothendieck, Feynman, and many other) if IQ were to be 80% heritable.
The idea that we mathematicians could all be delusional about our own life experience is emotionally-loaded, but this has nothing to do with ideology.
And, for completeness: I used to believe that math talent was innate, but my confrontation with high-level research made me change my mind. (So I really had no prior political objection to hereditarianism.)
A good chunk of IQ hereditarian claims are based on the 1990 Minnesota Study of Twins Reared Apart (Science Magazine) IQ study. DZ-apart twins (DZAs) constituted the study's control group. Critics have argued that the DZA IQ correlations were suppressed/hidden, and that if they hadn't been suppressed/hidden, the Minnesota researchers would have found no evidence in favor of above-zero IQ heritability. No one has ever shown that the critics are wrong, not even Bouchard, in his 2023 response article. Care to comment?
Eh, hereditarianism seemed to be the stronger argument to me despite me not wanting it to be true emotionally. It was only when I saw that it too has its problems (PGS portability, missing heritability, etc) that I changed my mind towards being more partial towards environmentalism.
Interestingly, better schools and pre-natal care and nutrition etc. all improve measures of intelligence AND intelligence is largely determined by forces outside of soclal engineer's control...
There are many things that evade our conscious control, and yet there are many things that we can control, and many more that it is worth trying to control, even if in the end we only manage to capture a fraction.
Can you direct me towards research (ideally with easily available data) about "better schools" having an impact? Everything I have ever come across implies that school "quality" has no measurable impact. School spending obviously has no impact, but what is the measure of "quality" where your can find a believable correlation with a reasonable intelligence metric?
Do you have any research to reference that displays "better schools" improve measures of intelligence? I have never come across any serious research that would suggest this. I have done some deep dives into data from 1970's school bussing, and I was shocked at how the school attended has zero impact on anything. The black students did no better and the white students did no worse. If you ever see researchers trying to justify those actions it is always an amazing example of data mining (ie "the male students over six feet tall born on an even year had 6% higher lifetime earnings...").
I am curious what is behind your statement. I agree on pre-natal care and nutrition (I would add exposure to heavy metals, which no one knew decades ago and turned out to be a massive influence), but "better schools" is more of a BS boilerplate from teachers' unions and poorly-educated municipal elected officials than fact.
"Rich kids are smarter than poor kinds in part because of their genes"
I see where we're going here. This is part of the determinism that fuels people like Stephen Miller and RFK Jr. If someone gets sick, they must have deserved it somehow; they were in fact predetermined to get sick by some divine plan, and therefore a) everyone who hasn't yet gotten sick (or say, in a car accident, or some other misfortune) has plot armour, and can't be touched. Meanwhile anyone anything bad happens to deserved it, since they weren't The Main Character.
Survivor bias.
This is the weirdness underlying the current eugenicists. They don't want to just kill certain swaths of the population, like the OG Nazis, which was horrific enough; the new, American Nazis have adopted a sort of American Health Insurer Nazism, in which they want to kill anyone who might have ended up exhibiting the weakness of getting sick.
It's a sort of calvinist thing. You worth was predetermined by some sort of God Sorting Machine, which decided where you would be when certain germs were floating through the air. Bad luck was your fault to begin with! It's very circular.
They use the language of genetics to imagine all of this, even though the vast majority of people are susceptible to things like, say, the measles. Genetics has nothing to do with who is rich and who isn't; this is again, Nazism by way of American Class Hierarchies. Basically medieval bloodline of kings descended from God, etc, but with a gloss of scientific-looking decoration on the top.
This is really how Nazis think, btw. If you think rich kids are inherently smarter you are probably a Nazi. But then, there are many types of smartness, and the idea that IQ is all that meaningful is pretty stupid. Most people who think so have very little social smarts, since their creepy ideas don't play well at parties.
If you open Wikipedia's page on Richard Hanania you will very quickly find that he is (was, if you believe him when he says he changed) white supremacist and wrote for Breitbart, as well as being a contributor to the planning stages of Project 2025, the current fascist project to take over america.
So to answer your question, "Yes, and we have documentary evidence that proves it".
You do realize that "White supremacist " simply means "person the author does not like." Racism is nasty and we need to work harder to root it out. White supremacy does not exist.
Can you provide this term? I missed at Cornell in my undergrad and Georgetown in grad school. These must be terrible places to study that subject. The term was never referenced. The first time I heard it was during Trump's first circus show, ahem, I mean campaign. I assume the expression was invented to downplay the abhorrent views of so many of his supporters.
"Racist" is just about the worst term anyone would want used to describe her/himself (surpassed only by "child molester." White supremacist is so absurd that one can laugh it off. Before 2016 many useless terms were invented or taken from the most embarrassing parts of American academia. We may not know if this nonsense was started by Chinese intelligence or Russian intelligence, but definitely our political system and online dialog have been driven by foreign intelligence since then. Clowns like those you debate are not Nazis. They are not that smart, and they do not share their views. Hanania is a tool, but he is not a Nazi. There are so many ways to cut him down, and silly rants end up doing the opposite. It does make one wonder if you are not working with him.
Nazis were socialists with STRONG feelings about social equality. Under Hitler Germans had high minimum wages, universal free health care, discounted vacations for workers and tons of other programs to make life better for the working class. The "Nazi" party was actually called the NSDAP (national socialist German workers' party). In Germany back then they were called "National Socialists." They HATED class hierarchies and viewed American income and living standard variances with disgust.
Everywhere you use the term "Nazi" it makes no sense. I know Americans dislike learning history, but please do not use words you clearly do not understand. I disliked that statement as well, but it was not in any way similar to any policies or public goals of the Nazis. You should use the term "bad people" perhaps? In addition, try to focus on what he wrote, not random foolish things you dislike. I agree with so much of what you say, but it is painful to read. The Nazis banned royal and noble titles. They HATED the old regime, Christianity and capitalism. The Nazis wrote all kinds of moronic books about "Interest rate slavery" and other idiocy, because they hated income inequality, inequality and public displays of wealth. Your comparisons would work if you get rid of all of those bizarre references to Nazis.
The National Socialists were bad people. They promoted bad things (Anti-Semitism, war, ...), but they were devoted to creating a new world where all Germans were taken care of, where business was always subservient to the public interest (however evil their definition), and they HATED inequality and class hierarchies.
This is really basic stuff. If you read Shirer's Rise and Fall of the Third Reich, it gives a pretty decent explanation of Nazi political views and public policy decisions. The Nazis HATED almost every aspect of American life. They believed that we were slaves to a cabal of Wall Street Jews in New York who controlled the world. They hated Christianity, and believed in "Progress." They often used that term. Evil cults often do, so decent liberal Americans NEVER should.
"The remaining 50% or so is everything including the prenatal environment, any diseases or developmental irregularities, family environment, schools, friends, books people have read, etc." Well, friends and books are certainly malleable! And these 50% altogether are also harder to measure, which opens space for hopes and aspirations (though perhaps of a less goal-oriented kind).
That said, I do find the 50% picture fairly cheerless (even knowing that I'm fairly high up on it), so I tend to agree with your wider point even while agreeing with David's arguments against taking the data at face value. The gulf between the twin studies and the numbers that a blank-slate view would require is just too large, and there is so much dynasticity in academia that hereditability should be the null hypothesis.
An optimistic way to look at it, even if the "accessible to agency" fraction is measured at a low value: this is a population average, it might well be that the people who try hard (for themselves or for their kids) do achieve substantial success, but there's just not many of them.
Also: 50% isn't proven to be the right figure, and IQ itself isn't the outcome that matters.
I commend you for the effort. If only strong counter arguments like this could be beamed into the heads of the other 3,499,999.
Reading this makes me feel like on some level whatever science I come in contact with I can’t trust unless I’ve done the work myself. It’s not true, but to see a post I fully believed as true turn out to have this level of debate is startling.
I feel ya, but this piece confirms that a disciplined, astute, and self-aware approach makes for very persuasive science indeed. The real culprit is the gee-wiz effect of modern media, the bread and butter of its commercial existence. Social media is culpable to a great extent, but the twin studies phenom’s media profile obviously pre-dates Century 21’s great contribution to humanity’s capacity for mass delusion. (Now if we could just get some of those purebred hereditarians to read the whole thing it might just make the world a nicer place!) As a 35 year high school teacher I never doubted the influence of genetics, but, having taught in rural, suburban, and inner city settings I never doubted the influence of social and environmental factors either. Now that I’m retired I’m thinking about working on my math - with renewed hope!
Hello, Dj Bracken. Thank you for your good work, providing lunch food for Utah school children regardless of their impoverished family circumstances. Paul Graham has returned to the topic and now it has morphed into a far right wing thing according to Paul:
"We have multiple reasons for wanting to believe nurture is more important than nature and none for wanting to believe the opposite (unless we = the far right, which we ≠), so it's not surprising we overestimate its effect. But man are kids' personalities inborn." see
Regarding Cremieux's Twitter/X post of Dec 2025, about heritability of IQ, and David's critique, you remarked,
"I feel like... science I come in contact with, I can’t trust unless I’ve done the work myself...to see a post I fully believed as true turn out to have this level of debate is startling."
I have an advanced degree in applied math; I worked for years as a statistician for a Medicaid program for children with special health care needs. The 2008 financial crisis ended that. Now I use statistics and probability for oversight of bank regulatory compliance.
I want to emphasize this: You need not worry about "trusting science" IF you check the source. Twitter, um, X posts aren't comparable to legit scholarly journal articles or (more accessibly) summaries for the public from Science https://www.science.org, the publication of the American Association for the Advancement of Science (AAAS).
If you didn't know, Cremieux is a fake name. This isn't the first time he's tweeted something iff-y, or so it seemed to me. Often, he is insightful and reliable! Regardless, Cremieux's Twitter posting is intended for discussion (with him or others). I view it as his hobby activity.
The same caveats apply to Substack. I question a few of David Bessis's counter-arguments to Cremieux's summary of heritability of IQ research in this post. I have a lot more questions about David's challenges to the veracity of the 3 (actually 2) studies, published circa 1958; that is the greater part of the post. David doesn't fully explain some of his work, makes some assumptions I want to know more about, etc. But that's okay too! I appreciate that Jeff made this effort and I learned from it.
Paul Graham was the lazy one, as he wrote about the subject, used it for a politically-tinged conclusion, yet didn't do any checks like Cremieux or Jeff, AND Paul has a huge platform!
Tweets and Substack aren't peer-reviewed. They aren't scholarly journal-quality. They aren't even held to journalistic reporting standards. Re the latter: I'm just as incredulous as Jeff about the conclusions in that NYTimes article about twins. It is NOT reassuring about science journalism! Sheesh... twins separated at birth get the same kind of dogs and name them same?!
Another point, perhaps g is 70-80% heritable, but IQ is less so, and math talent even less so. Just like height is more heritable than basketball ability.
I think you guys are looking for a conclusion rather than just looking at the evidence. “Yeah IQ might not be heritable but what it attempts to measure is.” What!? Why is it so important for intelligence to be sealed at birth for you? Maybe its because that kind of simplicity, ironic, gives you peace about the world. It explains so much. If the world is more complex, then you are on less stable ground and you must deal with the challenges that ground presents.
On the contrary, why does it seem so important to YOU that intelligence is not molded at birth? Indeed, it's much more convincing to suppose that it is YOUR skeptic crowd which, at root, is concerned less with finding the truth and more with a pleasant fantasy. Are you actually saying that "everyone has the same potential-ish and can work hard to achieve their dreams :)" is the complex, brutally honest and rigorous choice? Utterly laughable how you people try to talk down to hereditarian proponents.
This presumably goes both ways: maths ability could also be highly heritable when measured independently of the other items that attempt to measure G. Has this been done?
But I take your point that the non-g components of math ability probably are decently heritable too, even if less than the g one. It probably helps to be able to obsess over a particular problem for a few months. That sounds like something that is probably genetic, though less so than IQ. Still, I would guess that math ability, while fairly heritable, is less heritable than IQ.
Some of this is slightly inaccurate, maybe read Kevin Mitchell’s book ‘Innate’.
Just as anecdotal evidence, my mother was adopted. She met her biological family as an adult, and was stunned by their shared personality traits compared to her adoptive family. I’ve always found that compelling because I saw it myself. Admittedly, n=1 but there are numerous other cases like it.
I don't see that anyone has argued against the idea that many personality traits can be inherited or are somehow otherwise "innate".
What they have pointed out, however, is that attempts to show that intelligence is hereditary are generally not scientifically sound for a number of reasons.
Most of this is far beyond my intellectual pay grade, and in retrospect it’s obvious all the different studies used the same few data sets, but as an eighteen year old psychology major I vaguely thought that every time you wanted to run a heritability study, you had to go out and find a fresh group of identical twins who had been separated at birth and run experiments on them. How many of these twins could there possibly be?! I remember wondering. Surely at some point the scientists are going to run out! It’s funny and kind of delightful to discover, thirty years later, such a complicated story hiding behind that little flicker of confusion.
I caught Cremieux grossly misrepresenting statistical data on the link between vaccines and autism. He presented a twin study of MMR as statistical ‘proof’ that vaccines do not cause autism. I pointed out that the cited study compares just one vaccine against any other vaccines (no control for vaccination status except MMR), so it only shows, at best, that MMR is not more likely to cause autism than other vaccines. He didn’t deny my argument, but stopped short of conceding that his claim was misleading. An expert in statistics is not free to claim innocence on such a basic logical error, or they would be abrogating the status and reliability as an expert.
I’m glad to see you are a centrist! I think most hereditarians are in fact centrists (i.e., believe enviroment has a sizeable impact). But most environmentalists are almost “forced” to be blank slaters.
There is a reason for this: mathematically as you remove sources of environmental variance you are left with only sources of genetic variance. (And obviously as of yet it’s impossible to remove genetic variance.).
So, environmentalists are left with the issue that if they ever succeed in achieving their goal of perfect enviromental equality, they will only have succeeded in creating a world that is perfectly genetically deterministic.
So *that* is why they are blank slaters. They are forced into it by necessity.
Also, I know you focused on twin studies, but they are really only one piece of a very persuasive picture along with adoption studies and kinship studies, which don’t suffer many of the flaws you identified here and are overall quite consistent with twin studies. Twin studies should just be looked at as one piece of a large bayesian picture.
(E.g., google the Texas Adoption Project; this estimated heritabilty at 0.78 without using twins reared apart.)
I think that you are misframing this as a "nature vs nuture" opposition, while a lot of the variance is attributable to non-genetic factors that aren't amenable to socio-economic dimensions.
I don’t understand the range restriction counter. Heritability is always environmentally constrained (i.e., if somebody suffers from malnutrition heritability will obviously be impacted.)
Wouldn’t we want a heritability for “typical” environments? Why doesn’t couch heritability with the caveat that the envioronment is in fact typical?
I.e., what is the heritability for a typical student at Overland Park Kansas high school?
Your argument boils down to “heritability is low in really bad environments”.
Well, yeah. That is indisputable. Nobody is saying that heritability is 0.8 in sub-saharan Africa for instance.
If you want heritability for "typical environments", then you need to build a database of IQ variance among students coming from "typical environments."
IQ variance is 15 for the general population, but it is certainly much lower for these "typical" students.
So when you observe that the typical IQ gap between MZA twins is 6 points, you can't conclude "this is much smaller than the expected value of 15, therefore IQ is mostly heritable". You should conclude "this is somewhat smaller of the expected value of X (with X << 15), so IQ is somewhat heritable".
Besides, my argument doesn't boil down to “heritability is low in really bad environments".
It boils down to: "this is demonstrably bad science and the smoking gun is that Bouchard has spent the past 35 years refusing to release his control group data".
It is incorrect *without* the adjustment, of course.
I haven't looked at the methodology, but 0.4-0.8 is a pretty wide range ;)
[One issue with all these subtleties, which is behind my conclusions 1 & 2, is that model credibility naturally decreases with complexity, for good reasons (curse of dimensionality / p-hacking) and bad reasons (people, including me, tend to get bored...
I fundamentally understand the desire to estimate heritability, and I fundamentally understand the allure of MZA studies, twins reared together studies, and adoption studies, and I looked at them with an open eyes... my personal conclusion is that the core matter is too complex and messy for solutions to be clear-cut... It's a sad conclusion, not only that I'm happy to reach.]
> Heritability is, by construction, a population-level aggregate. Before it can inform policy-making (or even personal decision-making), it must be interpreted at the level of individuals.
Well, no, not really. An effect can be minor at the level of individuals but still be hugely important for group outcomes and society overall. For examples, a small difference in means or variance between two groups leads to much larger disparities at the tails (share of each group in the 1% extremes of the trait).
Yes and no. It may matter for the polygenic tails, but no-one knows for sure where one is situated (in the absence of an accurate test) and, for the "random" person, the effect is negligeable.
As for Scott Alexander's post, I had scanned through it but not fully read. My general feeling is that he's slowly moving away from his hereditarian priors (which I completely understand since I started out with the same priors — my earlier post attempts to respond to his "parable of talents" post: https://davidbessis.substack.com/p/beyond-nature-and-nurture). But this process takes time and I'm disappointed to see that he often continues to dismiss the centrist viewpoint (eg, I definitely don't view myself as "nurturist", as he labels us here https://www.astralcodexten.com/p/the-good-news-is-that-one-side-has) — but this is an evolving picture and he seems to be moving in the right direction.
BTW, I do hope he reads this post and finds it some merit (he's super smart, but he's not omniscient and he's not a statistician). I liked that he seems to have carefully read what Sasha wrote (despite Cremieux trying to dissuade him by disparaging Sasha and painting him as an ideologue) — this is a sign of being open on a topic where he started from a very rigid position.
That is a popular argument among people who want intelligence to be hereditary and among people who want various abilities to be gender linked, etc., but it assumes all sorts of unknown things about the distribution and phenomenon. Average life span among Danes may be significantly higher than average life span among Pakistani villagers, but that doesn't tell you anything about which population has more people of age 100+.
Despite my inability to really process a fair amount of this, I think I grasped the basic story of this author’s attempt to explain a complicated topic to others, but first to himself. Fascinating, and certainly one kind of essay that I would almost certainly never read if it weren’t on substack. Another thing drawing me to it is that @Rafe Meager restacked it. A Rafe Meager restacking often leads me to slog through material that’s puzzling and far above my pay grade, but also riveting when I start to understand pieces of it. To sum up— it’s good to inherit intelligence, but also good to subscribe to people whose minds can dance around yours. No matter how “smart” you are, it’s not a bad idea to have smart friends.
Your most important point: "For all their performative battles, hereditarians and blank-slatists operate within the same deterministic frame (genetic determinism vs social determinism), denying any meaningful role for human agency and the messy, noisy process we call life."
Yet most of the comments continue to assume that determinism of one type or another controls for 100% of outcomes. And by "outcomes" I don't mean test scores: I mean success in life. My view is that individual human agency, for those who choose to exercise it, is the dominant variable. Free will, which cannot be explained by deterministic models of the universe, nevertheless is axiomatic to all human thought, which otherwise is cosmic noise. This is what separates humans from jellyfish and gnus.
Do you know if anyone has done research with “hyperdonors” of sperm like Jonathan Jacob Meijer? Obviously this would have its own limitations, as zygotes don’t contribute genes in a predictable pattern and people undergoing in vitro fertilization are not a broad cohort, but 500 kids with a single father and separate households would be interesting.
The other part that is such nonsense in the whole heredity argument is the notion that genes are switches for broad phenotypical attributes. I have achieved a high level of success academically, but I think much of my skillset came from absurd oversensitivity (which sucks, btw). I think my brain had to cope with an excess of stimuli and became conditioned to pattern-creation and matching.
I don’t think I have some gene for good pattern matching.
Hasn’t it become fairly clear that an individual genome has limited predictive power with regard to the development of the individual? Rather, it seems that the role of the genetic material is more that of a library rather than a formational hierarchy. In other words, the entire chemical payload present in zygotes is at least as important as the genes themselves and the capacity for individuals to be influenced by environment is far greater than a system based simply on genetic heritability. Anyway, just my opinion, but it all seems to line up…
I read all of this and commend your effort and good faith intellectual pursuit. Kudos. Now that you’ve tackled the heritability variable, please dig into IQ. I was a little miffed that this notion (IQ), so clearly developed and contingent on environmental acquisition of information, was discussed as if it was fixed and static and measuring what it claimed to measure. I felt the piece would have benefitted from a more expansive discussion of what IQ is purported to measure/be and whether these tests get at that in a valid way. To interrogate IQ as valid, fixed, extant, etc. is all the more relevant to this discussion as the point of this article was to examine and challenge assumptions of the “purity” or “cleanliness” of twins reared apart studies. I think a rigorous analysis of IQ in the same spirit of this piece on heritability would make a valuable companion.
Ah, another long story. The issue is that IQ is mildy meaningful, and it's hard to build a debunk of the exaggeration of something that is mildly meaningful — the IQ mafia will instantly label me a flat-earther (they already do).
Ashamed to say I took those Jim Twin anecdotes at face value. I suppose the conformity is still striking, but that’s the 1950s for you. I don’t doubt genetics played a part, there’s just not the empirical record I thought. Man- psychology has a spotty record.
First-time reader here! I'd like you to know that this reads like a transcribed HBomberguy video and I mean that as the highest possible compliment. I'm going to show this to my mother!
Are parents of great mathematicians, mathematicians? If not then how did they get their genes? The idea that IQ is inheritable makes no sense. Ramanujan was a perfect falsification of this theory. His parents were not versed in mathematics at all. There is a component of nurture for creating mediocre mathematicians, but even that doesn't applies for great mathematicians.
I think IQ is the same, and not dependant on genetics, but possibly has a large component of nurture. IQ isn't even a great predictor of success in life.
Ramanujam grew up in a community known for intellectual rigor, deep understanding of scripture, and this usually included an interest in astrology, especially calculations of positions of different planets in the sky at specific moments. As someone from the same community, it helps you be good at sitting down with hard problems and persisting with them, and memorizing complex things. I was reciting 100-verse poems from memory at 3, and by 5 I was reasoning about scripture and finding patterns. And my upbringing was likely much much much less rigorous and immersive in this aspect than Ramanujam's would have been. Our community is really big on getting kids to sit down and learn, and reward precocity with even more knowledge. When I think back, the level of how much everyone around you tries to make you learned is insane. Western helicopter moms stand no chance in comparison (I get to compare because I'm this type of mom and my mother in law is an American early education expert who tutors geniuses and illiterate kids, and we both try to make my daughter learned. The level i expect and work towards mog hers). My uncle, no genius himself, would rock me to sleep with times tables enough that by age 5 I knew them till 10.
And I guess Ramanujam had divine intervention - his family deity seemed to bless him with the proofs according to his own accounts. That might be hard to replicate because not only do you have to be in a family that is historically taken care of by this deity, but you have to have the faith of a man in the early 20th century!
You confuse the moonlight for the sun. Environmental explanations are PLAUSIBLE to explain the stated circumstances. That does not mean they are PROVEN. Somehow you people never approach these with the level of rigor and skepticism you do hereditarianism. You never question how it happened that their parents became so obsessed with times tables that they read them to their children - it must have just "happened", I guess. Just chance. Ridiculous.
It never occurs to you that heredity explains these just as much, and more, than environmentalist hypotheses, and that the onus is on YOU to prove it otherwise. A "merely plausible" explanation is what allows concepts like the four humors and geocentrism to persist. Abandon pleasant fantasies and what you WANT to be true and find the f###ing truth.
Because that's how our community is expected to do our duty to the Gods. We're supposed to be the preservers of knowledge. Whatever little knowledge the parent has, we consider it our duty to inculcate it in our children. We also think the young mind is best for memorizing, and once you get older, you can't remember things as well.
Western parents read to their kids, almost to a fault. But they don't use that time to actually pass on much knowledge because they think children aren't capable of absorbing much. But folks in my community always know of some child who was reciting complex shlokas not long after they could say words, so we nurture that in children.
I see this in my own family. My husband thinks you must speak in simple words to children and it's too complex to explain how machines work, or that memorizing lists of things, like days of the week, months of the year etc is too much for children. I OTOH would recite them to her in the stroller when we took a walk or any moment i had her as a captive audience, right from birth, sing her poems written by Nobel laureates. She showed a preference for learning how things work, so I took her to factories and water treatment plants and Amazon warehouses. I found her playing 'assembly line' with her dolls.
If you see children being capable of learning at an early age, if you have experienced adults around you teaching you things at an early age, you'll do it too. If you didn't, you won't.
It's far from certain that Cyril Burt committed fraud, rather than simply being sloppy with data retention in the way many from his era were.
https://arthurjensen.net/wp-content/uploads/2014/06/1991-jensen-1.pdf
Most of this stuff is well known to researchers, as acknowledged, and I don't think that finding IQ is only 40% or 50% heritable will make people's political hopes and aspirations that much more realistic. The remaining 50% or so is everything including the prenatal environment, any diseases or developmental irregularities, family environment, schools, friends, books people have read, etc. There's just much less room for social intervention to create equality than assumed in public policy debates, where nobody will say that rich kids are smarter than poor kids in part because of their genes.
Why do you frame this in terms of "political hopes and aspirations" when this is absolutely not what is at stake in my critique?
(And re Burt: Jensen has his opinion, but it is far from representing the consensus.)
A key point is that the replication crisis has shown that all research and research publications that were not pre-registered are suspect, especially in the field of academic psychology. Confirmation bias is a major factor in the conclusions researchers draw behind the scenes, and to be fair, this observation applies to "environmentalist" research as well. It's not like Cyril Burt was a bad apple in an otherwise healthy barrel of psychology research. The replication crisis shows us that a sizable portion of the barrel contained rotten apples that made it past peer review. That, by the way, is the only valid defense of Burt's "study" I can come up with.
You talk about your emotional reaction to hereditarianism, which seems to suggest you’d rather it not be true for ideological reasons.
How do you jump from emotions to ideology? That is a crazy interpretation of my perspective!
As is explained in this post (and many of my other posts), what is fundamentally at stake for me is that my mathematical career (and more specifically my ascension to a level that I had long thought I was biologically incapable of) made me rethink my entire perspective on language, logic, intuition, and cognition.
This is a very important topic, adjacent to the IQ debate, but of prime importance to many practitioners of mathematics—including the many Fields medals and Abel prizes who have read and praised my book.
The adjacency is this: it is very unlikely that math talent could be as malleable as I think it is (alongside Descartes, Einstein, Grothendieck, Feynman, and many other) if IQ were to be 80% heritable.
The idea that we mathematicians could all be delusional about our own life experience is emotionally-loaded, but this has nothing to do with ideology.
And, for completeness: I used to believe that math talent was innate, but my confrontation with high-level research made me change my mind. (So I really had no prior political objection to hereditarianism.)
https://davidbessis.substack.com/p/beyond-nature-and-nurture
David, Hanania est une fraude totale. Il n'a pas les compétences techniques requises.
C'est probable — et ça explique certainement sa manière de répondre à côté du sujet !
A good chunk of IQ hereditarian claims are based on the 1990 Minnesota Study of Twins Reared Apart (Science Magazine) IQ study. DZ-apart twins (DZAs) constituted the study's control group. Critics have argued that the DZA IQ correlations were suppressed/hidden, and that if they hadn't been suppressed/hidden, the Minnesota researchers would have found no evidence in favor of above-zero IQ heritability. No one has ever shown that the critics are wrong, not even Bouchard, in his 2023 response article. Care to comment?
Sealioning
Eh, hereditarianism seemed to be the stronger argument to me despite me not wanting it to be true emotionally. It was only when I saw that it too has its problems (PGS portability, missing heritability, etc) that I changed my mind towards being more partial towards environmentalism.
So the nuanced take isn't "intelligence is largely genetic", but "intelligence is largely determined by forces outside of soclal engineer's control".
Which is, of course, false since better schools and pre-natal care and nutrition etc. all improve measures of intelligence.
Interestingly, better schools and pre-natal care and nutrition etc. all improve measures of intelligence AND intelligence is largely determined by forces outside of soclal engineer's control...
There are many things that evade our conscious control, and yet there are many things that we can control, and many more that it is worth trying to control, even if in the end we only manage to capture a fraction.
Life is messy, we all need to get over it.
Can you direct me towards research (ideally with easily available data) about "better schools" having an impact? Everything I have ever come across implies that school "quality" has no measurable impact. School spending obviously has no impact, but what is the measure of "quality" where your can find a believable correlation with a reasonable intelligence metric?
Do you have any research to reference that displays "better schools" improve measures of intelligence? I have never come across any serious research that would suggest this. I have done some deep dives into data from 1970's school bussing, and I was shocked at how the school attended has zero impact on anything. The black students did no better and the white students did no worse. If you ever see researchers trying to justify those actions it is always an amazing example of data mining (ie "the male students over six feet tall born on an even year had 6% higher lifetime earnings...").
I am curious what is behind your statement. I agree on pre-natal care and nutrition (I would add exposure to heavy metals, which no one knew decades ago and turned out to be a massive influence), but "better schools" is more of a BS boilerplate from teachers' unions and poorly-educated municipal elected officials than fact.
One of the problems with substack is that it tolerates racist drivel.
I don’t though. Bye.
You sound like a Nazi. Are you a Nazi?
"Rich kids are smarter than poor kinds in part because of their genes"
I see where we're going here. This is part of the determinism that fuels people like Stephen Miller and RFK Jr. If someone gets sick, they must have deserved it somehow; they were in fact predetermined to get sick by some divine plan, and therefore a) everyone who hasn't yet gotten sick (or say, in a car accident, or some other misfortune) has plot armour, and can't be touched. Meanwhile anyone anything bad happens to deserved it, since they weren't The Main Character.
Survivor bias.
This is the weirdness underlying the current eugenicists. They don't want to just kill certain swaths of the population, like the OG Nazis, which was horrific enough; the new, American Nazis have adopted a sort of American Health Insurer Nazism, in which they want to kill anyone who might have ended up exhibiting the weakness of getting sick.
It's a sort of calvinist thing. You worth was predetermined by some sort of God Sorting Machine, which decided where you would be when certain germs were floating through the air. Bad luck was your fault to begin with! It's very circular.
They use the language of genetics to imagine all of this, even though the vast majority of people are susceptible to things like, say, the measles. Genetics has nothing to do with who is rich and who isn't; this is again, Nazism by way of American Class Hierarchies. Basically medieval bloodline of kings descended from God, etc, but with a gloss of scientific-looking decoration on the top.
This is really how Nazis think, btw. If you think rich kids are inherently smarter you are probably a Nazi. But then, there are many types of smartness, and the idea that IQ is all that meaningful is pretty stupid. Most people who think so have very little social smarts, since their creepy ideas don't play well at parties.
If you open Wikipedia's page on Richard Hanania you will very quickly find that he is (was, if you believe him when he says he changed) white supremacist and wrote for Breitbart, as well as being a contributor to the planning stages of Project 2025, the current fascist project to take over america.
So to answer your question, "Yes, and we have documentary evidence that proves it".
You do realize that "White supremacist " simply means "person the author does not like." Racism is nasty and we need to work harder to root it out. White supremacy does not exist.
That is not what this term means, it has an incredibly widely accepted definition in political science.
Can you provide this term? I missed at Cornell in my undergrad and Georgetown in grad school. These must be terrible places to study that subject. The term was never referenced. The first time I heard it was during Trump's first circus show, ahem, I mean campaign. I assume the expression was invented to downplay the abhorrent views of so many of his supporters.
"Racist" is just about the worst term anyone would want used to describe her/himself (surpassed only by "child molester." White supremacist is so absurd that one can laugh it off. Before 2016 many useless terms were invented or taken from the most embarrassing parts of American academia. We may not know if this nonsense was started by Chinese intelligence or Russian intelligence, but definitely our political system and online dialog have been driven by foreign intelligence since then. Clowns like those you debate are not Nazis. They are not that smart, and they do not share their views. Hanania is a tool, but he is not a Nazi. There are so many ways to cut him down, and silly rants end up doing the opposite. It does make one wonder if you are not working with him.
Why you think that people wouldn't want to describe themselves as racist?
Retardmaxxing?
Nazis were socialists with STRONG feelings about social equality. Under Hitler Germans had high minimum wages, universal free health care, discounted vacations for workers and tons of other programs to make life better for the working class. The "Nazi" party was actually called the NSDAP (national socialist German workers' party). In Germany back then they were called "National Socialists." They HATED class hierarchies and viewed American income and living standard variances with disgust.
Everywhere you use the term "Nazi" it makes no sense. I know Americans dislike learning history, but please do not use words you clearly do not understand. I disliked that statement as well, but it was not in any way similar to any policies or public goals of the Nazis. You should use the term "bad people" perhaps? In addition, try to focus on what he wrote, not random foolish things you dislike. I agree with so much of what you say, but it is painful to read. The Nazis banned royal and noble titles. They HATED the old regime, Christianity and capitalism. The Nazis wrote all kinds of moronic books about "Interest rate slavery" and other idiocy, because they hated income inequality, inequality and public displays of wealth. Your comparisons would work if you get rid of all of those bizarre references to Nazis.
The National Socialists were bad people. They promoted bad things (Anti-Semitism, war, ...), but they were devoted to creating a new world where all Germans were taken care of, where business was always subservient to the public interest (however evil their definition), and they HATED inequality and class hierarchies.
This is really basic stuff. If you read Shirer's Rise and Fall of the Third Reich, it gives a pretty decent explanation of Nazi political views and public policy decisions. The Nazis HATED almost every aspect of American life. They believed that we were slaves to a cabal of Wall Street Jews in New York who controlled the world. They hated Christianity, and believed in "Progress." They often used that term. Evil cults often do, so decent liberal Americans NEVER should.
No reason to argue with idiots
I'm not American and you are a Nazi.
"The remaining 50% or so is everything including the prenatal environment, any diseases or developmental irregularities, family environment, schools, friends, books people have read, etc." Well, friends and books are certainly malleable! And these 50% altogether are also harder to measure, which opens space for hopes and aspirations (though perhaps of a less goal-oriented kind).
That said, I do find the 50% picture fairly cheerless (even knowing that I'm fairly high up on it), so I tend to agree with your wider point even while agreeing with David's arguments against taking the data at face value. The gulf between the twin studies and the numbers that a blank-slate view would require is just too large, and there is so much dynasticity in academia that hereditability should be the null hypothesis.
An optimistic way to look at it, even if the "accessible to agency" fraction is measured at a low value: this is a population average, it might well be that the people who try hard (for themselves or for their kids) do achieve substantial success, but there's just not many of them.
Also: 50% isn't proven to be the right figure, and IQ itself isn't the outcome that matters.
yeah
I commend you for the effort. If only strong counter arguments like this could be beamed into the heads of the other 3,499,999.
Reading this makes me feel like on some level whatever science I come in contact with I can’t trust unless I’ve done the work myself. It’s not true, but to see a post I fully believed as true turn out to have this level of debate is startling.
Thanks for doing the work to clarify.
Thank you! Now we’re down to 3,499,998 :)
I feel ya, but this piece confirms that a disciplined, astute, and self-aware approach makes for very persuasive science indeed. The real culprit is the gee-wiz effect of modern media, the bread and butter of its commercial existence. Social media is culpable to a great extent, but the twin studies phenom’s media profile obviously pre-dates Century 21’s great contribution to humanity’s capacity for mass delusion. (Now if we could just get some of those purebred hereditarians to read the whole thing it might just make the world a nicer place!) As a 35 year high school teacher I never doubted the influence of genetics, but, having taught in rural, suburban, and inner city settings I never doubted the influence of social and environmental factors either. Now that I’m retired I’m thinking about working on my math - with renewed hope!
Hello, Dj Bracken. Thank you for your good work, providing lunch food for Utah school children regardless of their impoverished family circumstances. Paul Graham has returned to the topic and now it has morphed into a far right wing thing according to Paul:
"We have multiple reasons for wanting to believe nurture is more important than nature and none for wanting to believe the opposite (unless we = the far right, which we ≠), so it's not surprising we overestimate its effect. But man are kids' personalities inborn." see
https://x.com/paulg/status/2081468716466803055
Regarding Cremieux's Twitter/X post of Dec 2025, about heritability of IQ, and David's critique, you remarked,
"I feel like... science I come in contact with, I can’t trust unless I’ve done the work myself...to see a post I fully believed as true turn out to have this level of debate is startling."
I have an advanced degree in applied math; I worked for years as a statistician for a Medicaid program for children with special health care needs. The 2008 financial crisis ended that. Now I use statistics and probability for oversight of bank regulatory compliance.
I want to emphasize this: You need not worry about "trusting science" IF you check the source. Twitter, um, X posts aren't comparable to legit scholarly journal articles or (more accessibly) summaries for the public from Science https://www.science.org, the publication of the American Association for the Advancement of Science (AAAS).
If you didn't know, Cremieux is a fake name. This isn't the first time he's tweeted something iff-y, or so it seemed to me. Often, he is insightful and reliable! Regardless, Cremieux's Twitter posting is intended for discussion (with him or others). I view it as his hobby activity.
The same caveats apply to Substack. I question a few of David Bessis's counter-arguments to Cremieux's summary of heritability of IQ research in this post. I have a lot more questions about David's challenges to the veracity of the 3 (actually 2) studies, published circa 1958; that is the greater part of the post. David doesn't fully explain some of his work, makes some assumptions I want to know more about, etc. But that's okay too! I appreciate that Jeff made this effort and I learned from it.
Paul Graham was the lazy one, as he wrote about the subject, used it for a politically-tinged conclusion, yet didn't do any checks like Cremieux or Jeff, AND Paul has a huge platform!
Tweets and Substack aren't peer-reviewed. They aren't scholarly journal-quality. They aren't even held to journalistic reporting standards. Re the latter: I'm just as incredulous as Jeff about the conclusions in that NYTimes article about twins. It is NOT reassuring about science journalism! Sheesh... twins separated at birth get the same kind of dogs and name them same?!
Another point, perhaps g is 70-80% heritable, but IQ is less so, and math talent even less so. Just like height is more heritable than basketball ability.
I think you guys are looking for a conclusion rather than just looking at the evidence. “Yeah IQ might not be heritable but what it attempts to measure is.” What!? Why is it so important for intelligence to be sealed at birth for you? Maybe its because that kind of simplicity, ironic, gives you peace about the world. It explains so much. If the world is more complex, then you are on less stable ground and you must deal with the challenges that ground presents.
On the contrary, why does it seem so important to YOU that intelligence is not molded at birth? Indeed, it's much more convincing to suppose that it is YOUR skeptic crowd which, at root, is concerned less with finding the truth and more with a pleasant fantasy. Are you actually saying that "everyone has the same potential-ish and can work hard to achieve their dreams :)" is the complex, brutally honest and rigorous choice? Utterly laughable how you people try to talk down to hereditarian proponents.
This presumably goes both ways: maths ability could also be highly heritable when measured independently of the other items that attempt to measure G. Has this been done?
Probably not
But I take your point that the non-g components of math ability probably are decently heritable too, even if less than the g one. It probably helps to be able to obsess over a particular problem for a few months. That sounds like something that is probably genetic, though less so than IQ. Still, I would guess that math ability, while fairly heritable, is less heritable than IQ.
Some of this is slightly inaccurate, maybe read Kevin Mitchell’s book ‘Innate’.
Just as anecdotal evidence, my mother was adopted. She met her biological family as an adult, and was stunned by their shared personality traits compared to her adoptive family. I’ve always found that compelling because I saw it myself. Admittedly, n=1 but there are numerous other cases like it.
I don't see that anyone has argued against the idea that many personality traits can be inherited or are somehow otherwise "innate".
What they have pointed out, however, is that attempts to show that intelligence is hereditary are generally not scientifically sound for a number of reasons.
Most of this is far beyond my intellectual pay grade, and in retrospect it’s obvious all the different studies used the same few data sets, but as an eighteen year old psychology major I vaguely thought that every time you wanted to run a heritability study, you had to go out and find a fresh group of identical twins who had been separated at birth and run experiments on them. How many of these twins could there possibly be?! I remember wondering. Surely at some point the scientists are going to run out! It’s funny and kind of delightful to discover, thirty years later, such a complicated story hiding behind that little flicker of confusion.
I caught Cremieux grossly misrepresenting statistical data on the link between vaccines and autism. He presented a twin study of MMR as statistical ‘proof’ that vaccines do not cause autism. I pointed out that the cited study compares just one vaccine against any other vaccines (no control for vaccination status except MMR), so it only shows, at best, that MMR is not more likely to cause autism than other vaccines. He didn’t deny my argument, but stopped short of conceding that his claim was misleading. An expert in statistics is not free to claim innocence on such a basic logical error, or they would be abrogating the status and reliability as an expert.
I’m glad to see you are a centrist! I think most hereditarians are in fact centrists (i.e., believe enviroment has a sizeable impact). But most environmentalists are almost “forced” to be blank slaters.
There is a reason for this: mathematically as you remove sources of environmental variance you are left with only sources of genetic variance. (And obviously as of yet it’s impossible to remove genetic variance.).
So, environmentalists are left with the issue that if they ever succeed in achieving their goal of perfect enviromental equality, they will only have succeeded in creating a world that is perfectly genetically deterministic.
So *that* is why they are blank slaters. They are forced into it by necessity.
Also, I know you focused on twin studies, but they are really only one piece of a very persuasive picture along with adoption studies and kinship studies, which don’t suffer many of the flaws you identified here and are overall quite consistent with twin studies. Twin studies should just be looked at as one piece of a large bayesian picture.
(E.g., google the Texas Adoption Project; this estimated heritabilty at 0.78 without using twins reared apart.)
I think that you are misframing this as a "nature vs nuture" opposition, while a lot of the variance is attributable to non-genetic factors that aren't amenable to socio-economic dimensions.
This is explained here: https://davidbessis.substack.com/p/beyond-nature-and-nurture
[As for adoption studies, they suffer from range-restriction, as discussed in my post & backed by the Pinker quote.]
I don’t understand the range restriction counter. Heritability is always environmentally constrained (i.e., if somebody suffers from malnutrition heritability will obviously be impacted.)
Wouldn’t we want a heritability for “typical” environments? Why doesn’t couch heritability with the caveat that the envioronment is in fact typical?
I.e., what is the heritability for a typical student at Overland Park Kansas high school?
Your argument boils down to “heritability is low in really bad environments”.
Well, yeah. That is indisputable. Nobody is saying that heritability is 0.8 in sub-saharan Africa for instance.
No, your reasoning is mathematically incorrect.
If you want heritability for "typical environments", then you need to build a database of IQ variance among students coming from "typical environments."
IQ variance is 15 for the general population, but it is certainly much lower for these "typical" students.
So when you observe that the typical IQ gap between MZA twins is 6 points, you can't conclude "this is much smaller than the expected value of 15, therefore IQ is mostly heritable". You should conclude "this is somewhat smaller of the expected value of X (with X << 15), so IQ is somewhat heritable".
Besides, my argument doesn't boil down to “heritability is low in really bad environments".
It boils down to: "this is demonstrably bad science and the smoking gun is that Bouchard has spent the past 35 years refusing to release his control group data".
It’s not “incorrect” per se, it just requires an adjustment for the lower variance.
Which people have done and still get 0.4-0.8 estimate for adoption studies.
It is incorrect *without* the adjustment, of course.
I haven't looked at the methodology, but 0.4-0.8 is a pretty wide range ;)
[One issue with all these subtleties, which is behind my conclusions 1 & 2, is that model credibility naturally decreases with complexity, for good reasons (curse of dimensionality / p-hacking) and bad reasons (people, including me, tend to get bored...
I fundamentally understand the desire to estimate heritability, and I fundamentally understand the allure of MZA studies, twins reared together studies, and adoption studies, and I looked at them with an open eyes... my personal conclusion is that the core matter is too complex and messy for solutions to be clear-cut... It's a sad conclusion, not only that I'm happy to reach.]
> Heritability is, by construction, a population-level aggregate. Before it can inform policy-making (or even personal decision-making), it must be interpreted at the level of individuals.
Well, no, not really. An effect can be minor at the level of individuals but still be hugely important for group outcomes and society overall. For examples, a small difference in means or variance between two groups leads to much larger disparities at the tails (share of each group in the 1% extremes of the trait).
(BTW, have you read https://www.astralcodexten.com/p/missing-heritability-much-more-than ?)
Yes and no. It may matter for the polygenic tails, but no-one knows for sure where one is situated (in the absence of an accurate test) and, for the "random" person, the effect is negligeable.
As for Scott Alexander's post, I had scanned through it but not fully read. My general feeling is that he's slowly moving away from his hereditarian priors (which I completely understand since I started out with the same priors — my earlier post attempts to respond to his "parable of talents" post: https://davidbessis.substack.com/p/beyond-nature-and-nurture). But this process takes time and I'm disappointed to see that he often continues to dismiss the centrist viewpoint (eg, I definitely don't view myself as "nurturist", as he labels us here https://www.astralcodexten.com/p/the-good-news-is-that-one-side-has) — but this is an evolving picture and he seems to be moving in the right direction.
BTW, I do hope he reads this post and finds it some merit (he's super smart, but he's not omniscient and he's not a statistician). I liked that he seems to have carefully read what Sasha wrote (despite Cremieux trying to dissuade him by disparaging Sasha and painting him as an ideologue) — this is a sign of being open on a topic where he started from a very rigid position.
That is a popular argument among people who want intelligence to be hereditary and among people who want various abilities to be gender linked, etc., but it assumes all sorts of unknown things about the distribution and phenomenon. Average life span among Danes may be significantly higher than average life span among Pakistani villagers, but that doesn't tell you anything about which population has more people of age 100+.
Despite my inability to really process a fair amount of this, I think I grasped the basic story of this author’s attempt to explain a complicated topic to others, but first to himself. Fascinating, and certainly one kind of essay that I would almost certainly never read if it weren’t on substack. Another thing drawing me to it is that @Rafe Meager restacked it. A Rafe Meager restacking often leads me to slog through material that’s puzzling and far above my pay grade, but also riveting when I start to understand pieces of it. To sum up— it’s good to inherit intelligence, but also good to subscribe to people whose minds can dance around yours. No matter how “smart” you are, it’s not a bad idea to have smart friends.
Your most important point: "For all their performative battles, hereditarians and blank-slatists operate within the same deterministic frame (genetic determinism vs social determinism), denying any meaningful role for human agency and the messy, noisy process we call life."
Yet most of the comments continue to assume that determinism of one type or another controls for 100% of outcomes. And by "outcomes" I don't mean test scores: I mean success in life. My view is that individual human agency, for those who choose to exercise it, is the dominant variable. Free will, which cannot be explained by deterministic models of the universe, nevertheless is axiomatic to all human thought, which otherwise is cosmic noise. This is what separates humans from jellyfish and gnus.
Amazing article!
Do you know if anyone has done research with “hyperdonors” of sperm like Jonathan Jacob Meijer? Obviously this would have its own limitations, as zygotes don’t contribute genes in a predictable pattern and people undergoing in vitro fertilization are not a broad cohort, but 500 kids with a single father and separate households would be interesting.
The other part that is such nonsense in the whole heredity argument is the notion that genes are switches for broad phenotypical attributes. I have achieved a high level of success academically, but I think much of my skillset came from absurd oversensitivity (which sucks, btw). I think my brain had to cope with an excess of stimuli and became conditioned to pattern-creation and matching.
I don’t think I have some gene for good pattern matching.
Hasn’t it become fairly clear that an individual genome has limited predictive power with regard to the development of the individual? Rather, it seems that the role of the genetic material is more that of a library rather than a formational hierarchy. In other words, the entire chemical payload present in zygotes is at least as important as the genes themselves and the capacity for individuals to be influenced by environment is far greater than a system based simply on genetic heritability. Anyway, just my opinion, but it all seems to line up…
I read all of this and commend your effort and good faith intellectual pursuit. Kudos. Now that you’ve tackled the heritability variable, please dig into IQ. I was a little miffed that this notion (IQ), so clearly developed and contingent on environmental acquisition of information, was discussed as if it was fixed and static and measuring what it claimed to measure. I felt the piece would have benefitted from a more expansive discussion of what IQ is purported to measure/be and whether these tests get at that in a valid way. To interrogate IQ as valid, fixed, extant, etc. is all the more relevant to this discussion as the point of this article was to examine and challenge assumptions of the “purity” or “cleanliness” of twins reared apart studies. I think a rigorous analysis of IQ in the same spirit of this piece on heritability would make a valuable companion.
Ah, another long story. The issue is that IQ is mildy meaningful, and it's hard to build a debunk of the exaggeration of something that is mildly meaningful — the IQ mafia will instantly label me a flat-earther (they already do).
Ashamed to say I took those Jim Twin anecdotes at face value. I suppose the conformity is still striking, but that’s the 1950s for you. I don’t doubt genetics played a part, there’s just not the empirical record I thought. Man- psychology has a spotty record.
-Sage
First-time reader here! I'd like you to know that this reads like a transcribed HBomberguy video and I mean that as the highest possible compliment. I'm going to show this to my mother!
Are parents of great mathematicians, mathematicians? If not then how did they get their genes? The idea that IQ is inheritable makes no sense. Ramanujan was a perfect falsification of this theory. His parents were not versed in mathematics at all. There is a component of nurture for creating mediocre mathematicians, but even that doesn't applies for great mathematicians.
I think IQ is the same, and not dependant on genetics, but possibly has a large component of nurture. IQ isn't even a great predictor of success in life.
Ramanujam grew up in a community known for intellectual rigor, deep understanding of scripture, and this usually included an interest in astrology, especially calculations of positions of different planets in the sky at specific moments. As someone from the same community, it helps you be good at sitting down with hard problems and persisting with them, and memorizing complex things. I was reciting 100-verse poems from memory at 3, and by 5 I was reasoning about scripture and finding patterns. And my upbringing was likely much much much less rigorous and immersive in this aspect than Ramanujam's would have been. Our community is really big on getting kids to sit down and learn, and reward precocity with even more knowledge. When I think back, the level of how much everyone around you tries to make you learned is insane. Western helicopter moms stand no chance in comparison (I get to compare because I'm this type of mom and my mother in law is an American early education expert who tutors geniuses and illiterate kids, and we both try to make my daughter learned. The level i expect and work towards mog hers). My uncle, no genius himself, would rock me to sleep with times tables enough that by age 5 I knew them till 10.
And I guess Ramanujam had divine intervention - his family deity seemed to bless him with the proofs according to his own accounts. That might be hard to replicate because not only do you have to be in a family that is historically taken care of by this deity, but you have to have the faith of a man in the early 20th century!
You confuse the moonlight for the sun. Environmental explanations are PLAUSIBLE to explain the stated circumstances. That does not mean they are PROVEN. Somehow you people never approach these with the level of rigor and skepticism you do hereditarianism. You never question how it happened that their parents became so obsessed with times tables that they read them to their children - it must have just "happened", I guess. Just chance. Ridiculous.
It never occurs to you that heredity explains these just as much, and more, than environmentalist hypotheses, and that the onus is on YOU to prove it otherwise. A "merely plausible" explanation is what allows concepts like the four humors and geocentrism to persist. Abandon pleasant fantasies and what you WANT to be true and find the f###ing truth.
Because that's how our community is expected to do our duty to the Gods. We're supposed to be the preservers of knowledge. Whatever little knowledge the parent has, we consider it our duty to inculcate it in our children. We also think the young mind is best for memorizing, and once you get older, you can't remember things as well.
Western parents read to their kids, almost to a fault. But they don't use that time to actually pass on much knowledge because they think children aren't capable of absorbing much. But folks in my community always know of some child who was reciting complex shlokas not long after they could say words, so we nurture that in children.
I see this in my own family. My husband thinks you must speak in simple words to children and it's too complex to explain how machines work, or that memorizing lists of things, like days of the week, months of the year etc is too much for children. I OTOH would recite them to her in the stroller when we took a walk or any moment i had her as a captive audience, right from birth, sing her poems written by Nobel laureates. She showed a preference for learning how things work, so I took her to factories and water treatment plants and Amazon warehouses. I found her playing 'assembly line' with her dolls.
If you see children being capable of learning at an early age, if you have experienced adults around you teaching you things at an early age, you'll do it too. If you didn't, you won't.