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It's interesting that you cite that Plomin article, since it actually concludes that only a small proportion of intelligence is genetically inherited. To quote:

by pcrh 5y ago

It's interesting that you cite that Plomin article, since it actually concludes that only a small proportion of intelligence is genetically inherited. To quote: >Using years of education rather than intelligence per se, the meta-analysis mentioned earlier with 125 000 individuals in a discovery sample yielded a GPS that accounted for 2 and 3% in two independent samples.16 More variance in intelligence is likely to be explained with GPS derived from larger samples, whole-genome sequencing and more novel strategies such as using networks of functionally linked genes. Accounting for 2-3% of variance in intelligence through genetics is pretty weak support for genetics being an important contributor to variation in intelligence (however measured). The denialism here lies with those who wish to believe that intelligence is largely genetically determined, rather than socially and environmentally determined.

xyzzyz 5y ago
You completely misunderstand the part you quote. What Plomin is saying is not that genetic heritability accounts for only 2-3% of the variance, but rather the GPSs, that is, the polygenic scores. What that means is that we can now point to concrete genes that contribute to intelligence, and assign them weights that tell us the significance of this contribution. This means that this 2-3% figure is not about reality of genetic contribution to intelligence on the ground, but rather about our explicit understanding thereof in 2014, when this article was originally published. Since then, our polygenic scores have significantly improved: for example, Lee et al in 2018 constructed polygenic scores that describe 11-13% of variance, a significant improvement over 2-3% result Plomin cites. There are probably even better results now, as the progress in the area is quick. Of course, 11-13% is still short of 80%+ that we already know is determined by genes, but our explicit understanding is slowly getting there. Importantly, as we get there, the goalposts of critics are constantly shifting: when we couldn’t point out to specific genes, the entire notion of heritability was attacked. Now that we can, the alleged problems are with spurious correlations resulting from population stratification etc. Alas, the science moves forward, despite fierce opposition. https://www.nature.com/articles/s41588-018-0147-3 https://www.nature.com/articles/s41588-018-0147-3 > The denialism here lies with those who wish to believe that intelligence is largely genetically determined, rather than socially and environmentally determined. I think your inability to distinguish between heritability and polygenic scores makes you thoroughly unqualified to make statements like that.
- pcrh 5y ago
  Polygenic scores are measures of the contributions of many genes to hereditability, what else do you think they are? There are two questions here: 1) What genes contribute to human intelligence? Evidently there are some, as the structure of the brain humans are uniquely endowed with at birth is mostly determined genetically. 2) Do common variations in these genes contribute to common variations in human intelligence? For 2) the answer is categorically "a few percent at most", even according to the sources you provide yourself. It's pointless denying this fact. Repeating that ~80% of variation in intelligence is genetic is displaying a limited understanding of inheritance. To answer 1) it may be possible to identify those genes that contribute to intelligence by performing large scale genetic studies to identify the rare cases where a small signal is detected from one or several of these (a polygenic test, for example, as you are fond of). Once these genes have been identified, one could then in theory investigate how they function, etc, in order to better understand the genetic basis of human intelligence, but it is unlikely to help understand the basis of the difference in intelligence between individuals.
  - xyzzyz 5y ago
    > Polygenic scores are measures of the contributions of many genes to hereditability, what else do you think they are? They are not “measures” in the same sense measuring tape is a measure of length. They are like credit scores: they are useful to predict likelihood of defaulting on a loan, but they do not give you full understanding of the entire reality on the ground. With better constructed credit scores you can get better at predicting defaults, just like Lee et al got better at predicting educational attainment than the 2-3% figure Plomin quoted. No sane person would say that Experian credit scores give you complete understanding of given persons credit ability and their future credit behavior, and no sane person will tell you that polygenic scores of intelligence/educational attainment give you complete picture of a person’s intelligence or education. Do you understand it now? If you’re still confused, try to think about this: if what Plomin meant, like you suggest, that genes only explain 2-3% of variance in educational attainment, how is it possible that only 4 years later, Lee et al exhibited PGS explaining 11-13% of variance? Have genes got 4 times stronger in 4 years? > For 2) the answer is categorically "a few percent at most", even according to the sources you provide yourself. No, it is not. I encourage you to put some effort into understanding what is being talked about here.

by pcrh 5y ago

xyzzyz 5y ago

You completely misunderstand the part you quote. What Plomin is saying is not that genetic heritability accounts for only 2-3% of the variance, but rather the GPSs, that is, the polygenic scores. What that means is that we can now point to concrete genes that contribute to intelligence, and assign them weights that tell us the significance of this contribution. This means that this 2-3% figure is not about reality of genetic contribution to intelligence on the ground, but rather about our explicit understanding thereof in 2014, when this article was originally published. Since then, our polygenic scores have significantly improved: for example, Lee et al in 2018 constructed polygenic scores that describe 11-13% of variance, a significant improvement over 2-3% result Plomin cites. There are probably even better results now, as the progress in the area is quick. Of course, 11-13% is still short of 80%+ that we already know is determined by genes, but our explicit understanding is slowly getting there. Importantly, as we get there, the goalposts of critics are constantly shifting: when we couldn’t point out to specific genes, the entire notion of heritability was attacked. Now that we can, the alleged problems are with spurious correlations resulting from population stratification etc. Alas, the science moves forward, despite fierce opposition. https://www.nature.com/articles/s41588-018-0147-3 https://www.nature.com/articles/s41588-018-0147-3 > The denialism here lies with those who wish to believe that intelligence is largely genetically determined, rather than socially and environmentally determined. I think your inability to distinguish between heritability and polygenic scores makes you thoroughly unqualified to make statements like that.

pcrh 5y ago
Polygenic scores are measures of the contributions of many genes to hereditability, what else do you think they are? There are two questions here: 1) What genes contribute to human intelligence? Evidently there are some, as the structure of the brain humans are uniquely endowed with at birth is mostly determined genetically. 2) Do common variations in these genes contribute to common variations in human intelligence? For 2) the answer is categorically "a few percent at most", even according to the sources you provide yourself. It's pointless denying this fact. Repeating that ~80% of variation in intelligence is genetic is displaying a limited understanding of inheritance. To answer 1) it may be possible to identify those genes that contribute to intelligence by performing large scale genetic studies to identify the rare cases where a small signal is detected from one or several of these (a polygenic test, for example, as you are fond of). Once these genes have been identified, one could then in theory investigate how they function, etc, in order to better understand the genetic basis of human intelligence, but it is unlikely to help understand the basis of the difference in intelligence between individuals.
- xyzzyz 5y ago
  > Polygenic scores are measures of the contributions of many genes to hereditability, what else do you think they are? They are not “measures” in the same sense measuring tape is a measure of length. They are like credit scores: they are useful to predict likelihood of defaulting on a loan, but they do not give you full understanding of the entire reality on the ground. With better constructed credit scores you can get better at predicting defaults, just like Lee et al got better at predicting educational attainment than the 2-3% figure Plomin quoted. No sane person would say that Experian credit scores give you complete understanding of given persons credit ability and their future credit behavior, and no sane person will tell you that polygenic scores of intelligence/educational attainment give you complete picture of a person’s intelligence or education. Do you understand it now? If you’re still confused, try to think about this: if what Plomin meant, like you suggest, that genes only explain 2-3% of variance in educational attainment, how is it possible that only 4 years later, Lee et al exhibited PGS explaining 11-13% of variance? Have genes got 4 times stronger in 4 years? > For 2) the answer is categorically "a few percent at most", even according to the sources you provide yourself. No, it is not. I encourage you to put some effort into understanding what is being talked about here.