[A_D_E_P_T]

I don't doubt that there are methodological and empirical problems all around. The scientific literature on these points is a mess.

We might want to look at the fundamentals: How is IQ qualitatively different from height, eye color, schizophrenia -- or any other highly complex, heritable polygenic trait? (One could also extend this to the many traits that animal breeders keep an eye on.) None of them have been fully pinned-down yet, but I don't believe that they can't be fully described in principle.

It's true that GWAS for intelligence explains <5% of variance today, but GWAS for height was in the same position a decade ago. Today polygenic scores for height predict over 40% of variance.

[tptacek]

One obvious difference between what is known about the heritability of height and what is known about the heritability of intelligence or educational achievement is that when you put height heritability to the test, for instance by checking to see if the intra-family studies agree with the population-level studies, the height heritability stuff holds up, and the EA/IQ stuff does not. Another might be that successive rounds of study of simple phenotypical traits like height have not demolished previous estimates of heritability, while that has in fact happened in the EA/IQ case.

All this happens before we even reach questions about test-test reliability of IQ, or of whether gene-environmental interactions are uniform between Europe and other population cohorts (they do not appear to be!). It defines away SES confounding (which appears to be a significant issue). It has thus far largely ignored epigenetics. And, of course, for it to mean anything, the hypothesis also has to defend the idea that IQ/EA, at least in its genetic component, is immutable.

All that aside, I'm mostly just here to say that simple heritability statistics don't say what people on HN seem to think they say.