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Right. I mean, the evidence is there that intelligence is at least somewhat heritable. But the evidence is that IQ (a measure of intelligence, rather than “intelligence” itself) is only moderately heritable at best, and that differences in socioeconomic status can overwhelm differences due to genetics. (This is not surprising, by the way – something can be very highly heritable, but entirely modified by the environment. Some genetic diseases like phenylketonuria are highly heritable and penetrant, but if children with the mutations are picked out at birth and fed a phenylalanine-free diet, they will never develop the disease.)</p>
<p>Theoretically, we have the tools in genetics and genomics to start discovering intelligence-related genes through genome-wide association studies. In practice, I think it’s going to be pretty difficult, because intelligence is obviously polygenic and because our yardstick to measure who has it and who doesn’t is pretty crude.</p>