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3.5% genetic association with intelligence means that 96.5% is not genetic. So your your citation does not support a strong link between genetics and intellige

• gwern 7y ago
  > 3.5% genetic association with intelligence means that 96.5% is not genetic. No. It does not mean that. As I literally just explained to you: a specific PGS variance != SNP heritability != heritability. (How could you possibly think that when I also just explained to you in my other comment that the current IQ SOTA is 11% and you replied acknowledging as much?) The best estimate of intelligence heritability in adulthood at the peak, using measurement-error-corrected estimates, is 70-80%. Very far from 3.5%. Or 11%, or 30%, or 50% for that matter.
  • pcrh 7y ago
    "Heritability" includes non-genetic factors, and combined with genetic factors accounts for ~50% of variation in intelligence. For genetic factors alone, the consensus so far is that there is very weak correlation of genetic variation with intelligence, unless a not quite-yet-established polygenic score is constructed. To wit: >From the 1990s until 2017 no replicable associations were found. GPS from these early GWAS, which we refer to as ‘IQ1’, predicted only 1% of the variance of intelligence in independent samples. It became clear that the problem was power: the largest effect sizes of associations between individual single nucleotide polymorphisms (SNPs) and intelligence were extremely small, accounting for less than 0.05% of the variance of intelligence. However, things got "better": >in 2016, a second meta-analytic GWAS analysis with a sample size of 294,000 identified 74 significant loci30. This analysis produced a GPS, EA2, that predicted 3% of the variance in years of education on average in independent samples30. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5985927/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5985927/ It stretches the imagination how one would go from these numbers to claiming that "The best estimate of intelligence heritability in adulthood at the peak, using measurement-error-corrected estimates, is 70-80%.
    • gwern 7y ago
      > "Heritability" includes non-genetic factors, and combined with genetic factors accounts for ~50% of variation in intelligence. No, it doesn't. Heritability is intended and defined to include genetic factors only, unless you are referring to indirect genetic effects which are mediated through the environment but are still genetic in origin. > For genetic factors alone, the consensus so far is that there is very weak correlation of genetic variation with intelligence, unless a not quite-yet-established polygenic score is constructed. To wit: You are again being extremely misleading and selective in your quote-mining, and you omit all of the qualifiers that Plomin & Stumm include, eg "Recent genome-wide association studies have successfully identified inherited genome sequence differences" - 'identified genome sequence differences' does not imply that they are the only genes involved. Merely that some have been identified, and more will be. As they then go on to point out in the parts of the review you ignore, future GWASes will surely make much more progress in identifying SNPs, and approach the SNP heritability ceiling of ~30% given enough data. > It stretches the imagination how one would go from these numbers to claiming that "The best estimate of intelligence heritability in adulthood at the peak, using measurement-error-corrected estimates, is 70-80%. Er, because I'm not talking about SNP heritability estimates. I am talking about estimates from twin studies, adoption studies, and MZA studies, which estimate total genetic contributions. The lower-bound is 50%, you don't get anything lower from any twin studies, and this is deflated by the fact that many twin studies are looking at young kids and the Wilson Effect has not yet kicked in; this is then further deflated by the fact that they use noisy IQ measurements, which inflate the error variance component and hide the shared-environment/heritability components. Correct for those, and you get up to 70-80%. All of this is covered in the Plomin textbook cited there, starting pg171, where they cover things like how MZA designs deliver 72% heritability estimates and they explicitly mention that measurement error biases downwards ('Corrected for unreliability of measurement, heritability estimates would be higher...'). They are being highly conservative by using a lower bound of 50%, and they are wrong to, because as I already mentioned family-GCTA/GREML-KIN indicates that semi-rare variants alone get you up to 50% heritability, so we can be sure that 50% is a considerable underestimate (which is consistent with their expanded textbook discussion noting that the real heritability is much higher).
      • 7y ago