> we know nearly nothing about the effects of variation on complex traits like intelligence
This is changing at an astonishing rate, though. The development of GWAS combined with huge genetic datasets and associated IQ test information has opened the floodgates to finding more and more genes that predict the variation in IQ. Of course, it's still an open question whether these have other effects, and whether their effects are additive (linear), but the field does seem to be making extremely rapid progress...
'gwern has put together some links on genetic associations with IQ:
This is changing at an astonishing rate, though. The development of GWAS combined with huge genetic datasets and associated IQ test information has opened the floodgates to finding more and more genes that predict the variation in IQ. Of course, it's still an open question whether these have other effects, and whether their effects are additive (linear), but the field does seem to be making extremely rapid progress...
'gwern has put together some links on genetic associations with IQ:
https://www.gwern.net/Mistakes#intelligence