Missing Heritability: Much More Than You Wanted To Know
Release Date: 07/01/2025
Astral Codex Ten Podcast
The Story So Far The mid-20th century was the golden age of nurture. Psychoanalysis, behaviorism, and the spirit of the ‘60s convinced most experts that parents, peers, and propaganda were the most important causes of adult personality. Starting in the 1970s, the pendulum swung the other way. Twin studies shocked the world by demonstrating that most behavioral traits - especially socially relevant traits like IQ - were substantially genetic. Typical estimates for adult IQ found it was about 60% genetic, 40% unpredictable, and barely related at all to parenting or family environment. By the...
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The first cohort of ACX Grants was announced in , the second in . In 2022, I posted for the first cohort. Now, as I start thinking about a third round, I’ve collected one-year updates on the second and three-year updates on the first. Many people said my request for updates went to their spam folder; relatedly, many people have not yet sent in their updates. If you’re a grantee who didn’t see my original email, but you do see this post, please fill in the update form . All quote blocks are the grantees’ own words; text outside of quote blocks is my commentary.
info_outlineAstral Codex Ten Podcast
This is where if two copies of Claude talk to each other, they end up spiraling into rapturous discussion of spiritual bliss, Buddhism, and the nature of consciousness. From the : Anthropic swears they didn’t do this on purpose; when they ask Claude why this keeps happening, Claude can’t explain. Needless to say, this has made lots of people freak out / speculate wildly. I think there are already a few good partial explanations of this (especially Nostalgebraist ), but they deserve to be fleshed out and spread more fully.
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This is another heuristic from the same place as . If someone proves you are absolutely, 100% wrong about something, it’s polite to say “Oh, I guess I was wrong, sorry” before launching into your next argument. That is, instead of:
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People don’t like nitpickers. “He literally did the WELL AKTUALLY!” If you say Joe Criminal committed ten murders and five rapes, and I object that it was actually only six murders and two rapes, then why am I “defending” Joe Criminal? Because if it’s worth your time to lie, it’s worth my time to correct it.
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There’s a long-running philosophical argument about the conceivability of otherwise-normal people who are not conscious, aka . This has spawned a shorter-running (only fifteen years!) rationalist sub-argument on the topic. The last time I checked its status was , which says: 1. Both Yudkowsky and Chalmers agree that humans possess “qualia”. 2. Chalmers argues that a superintelligent being which somewhow knew the positions of all particles in a large region of the Universe would need to be told as an additional fact that any humans (or other minds possessing qualia) in this region of...
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It's time to narrow the 141 entries in the to about a dozen finalists. I can't read 141 reviews alone, so I need your help. Please pick as many as you have time for, read them, and rate them . Don’t read them in order! If you read them in order, I’ll have 1,000 votes on the first review, 500 on the second, and so on to none in the second half. Either pick a random review (thanks to Taymon for making a random-review-chooser script ) or scroll through the titles until you find one that catches your interest - you can see individual entries here (thanks to a reader for collating them): ...
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A guest post by Brandon Hendrickson [Editor’s note: I accept guest posts from certain people, especially past Book Review Contest winners. Brandon Hendrickson, whose won the 2023 contest, has taken me up on this and submitted this essay. He writes at and will be at this weekend, where he and Jack Despain Zhou aka TracingWoodgrains will be doing a live conversation about education.] I began my of a couple years back with a rather simple question: Could a new kind of school make the world rational? What followed, however, was a sprawling distillation of one scholar’s answer that I...
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Tyler Cowen of Marginal Revolution continues to disagree with my . Going through piece by piece, slightly out of order: Scott takes me to be endorsing Rubio’s claim that the third-party NGOs simply pocket the money. In reality my fact check with o3 found (correctly) that the money was “channelled through” the NGOs, not pocketed. Scott lumps my claim together with Rubio’s as if we were saying the same thing. My very next words (“I do understand that not all third party allocations are wasteful…”) show a clear understanding that the money is channeled, not pocketed, and makes...
info_outlineThe Story So Far
The mid-20th century was the golden age of nurture. Psychoanalysis, behaviorism, and the spirit of the ‘60s convinced most experts that parents, peers, and propaganda were the most important causes of adult personality.
Starting in the 1970s, the pendulum swung the other way. Twin studies shocked the world by demonstrating that most behavioral traits - especially socially relevant traits like IQ - were substantially genetic. Typical estimates for adult IQ found it was about 60% genetic, 40% unpredictable, and barely related at all to parenting or family environment.
By the early 2000s, genetic science reached a point where scientists could start pinpointing the particular genes behind any given trait. Early candidate gene studies, which hoped to find single genes with substantial contributions to IQ, depression, or crime, mostly failed. They were replaced with genome wide association studies, which accepted that most interesting traits were polygenic - controlled by hundreds or thousands of genes - and trawled the whole genome searching for variants that might explain 0.1% or even 0.01% of the pie. The goal shifted toward polygenic scores - algorithms that accepted thousands of genes as input and spit out predictions of IQ, heart disease risk, or some other outcome of interest.
The failed candidate gene studies had sample sizes in the three or four digits. The new genome-wide studies needed five or six digits to even get started. It was prohibitively difficult for individual studies to gather so many subjects, genotype them, and test them for the outcome of interest, so work shifted to big centralized genome repositories - most of all the UK Biobank - and easy-to-measure traits. Among the easiest of all was educational attainment (EA), ie how far someone had gotten in school. Were they a high school dropout? A PhD? Somewhere in between? This correlated with all the spicy outcomes of interest people wanted to debate - IQ, wealth, social class - while being objective and easy to ask about on a survey.
Twin studies suggested that IQ was about 60% genetic, and EA about 40%. This seemed to make sense at the time - how far someone gets in school depends partly on their intelligence, but partly on fuzzier social factors like class / culture / parenting. The first genome-wide studies and polygenic scores found enough genes to explain 2%pp1 of this 40% pie. The remaining 38%, which twin studies deemed genetic but where researchers couldn’t find the genes - became known as “the missing heritability” or “the heritability gap”.
Scientists came up with two hypothesis for the gap, which have been dueling ever since:
- Maybe twin studies are wrong.
- Maybe there are genes we haven’t found yet
For most of the 2010s, hypothesis 2 looked pretty good. Researchers gradually gathered bigger and bigger sample sizes, and found more and more of the missing heritability. A big 2018 study increased the predictive power of known genes from 2% to 10%. An even bigger 2022 study increased it to 14%, and current state of the art is around 17%. Seems like it was sample size after all! Once the samples get big enough we’ll reach 40% and finally close the gap, right?
This post is the story of how that didn’t happen, of the people trying to rehabilitate the twin-studies-are-wrong hypothesis, and of the current status of the debate. Its most important influence/foil is Sasha Gusev, whose blog The Infintesimal introduced me to the new anti-hereditarian movement and got me to research it further, but it’s also inspired by Eric Turkheimer, Alex Young (not himself an anti-hereditarian, but his research helped ignite interest in this area), and Awais Aftab.
(while I was working on this draft, the East Hunter Substack wrote a similar post. Theirs is good and I recommend it, but I think this one adds enough that I’m publishing anyway)
https://www.astralcodexten.com/p/missing-heritability-much-more-than