This is best answered by a competent geneticist, so neither I nor Nathan Cofnas are qualified.
I don't know whether Cofnas' gripe about '
The majority of philosophers and social scientists' is true or not, but those people are also not the best people to comment on the issue, nor to carry out experiments on the matter.
Meanwhile, geneticists
have been carrying out studies on the genetic basis of intelligence, and what they've found (as I understand it) is that hundreds of genes play a role in intelligence, and each of them is only responsible for a tiny fraction of the human variation in intelligence. And I doubt it is an 'additive' process. If gene A is associated with +0.03 IQ points, and gene W is associated with -0.01 IQ points, then the effect of having both genes is not necessarily +0.02 IQ points. (I doubt this is actually how such things are measured at all, but hopefully my point is clear.) The sheer number of genes that play a role, and the great genetic variation
within racial groups makes me doubt that there will be any clear 'racial genes' that play a significant role in intelligence.
The racial differences on performance on IQ tests (inasmuch as that is a measure of 'intelligence') is quite large. The effects of each individual gene on intelligence is quite small. It seems to me that if the racial difference in IQ performance were due to genetic differences, it would shout from the data. It doesn't.
---
From Wikipedia on
genetics of race and intelligence.
Intelligence is a polygenic trait. This means that intelligence is under the influence of several genes, possibly several thousand. The effect of most individual genetic variants on intelligence is thought to be very small, well below 1% of the variance in g. Current studies using quantitative trait loci have yielded little success in the search for genes influencing intelligence. Robert Plomin is confident that QTLs responsible for the variation in IQ scores exist, but due to their small effect sizes, more powerful tools of analysis will be required to detect them.[138] Others assert that no useful answers can be reasonably expected from such research before an understanding of the relation between DNA and human phenotypes emerges.[82] Several candidate genes have been proposed to have a relationship with intelligence.[139][140] However, a review of candidate genes for intelligence published in Deary, Johnson & Houlihan (2009) failed to find evidence of an association between these genes and general intelligence, stating "there is still almost no replicated evidence concerning the individual genes, which have variants that contribute to intelligence differences"
