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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…
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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 > 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.