Half Sigma discovers “epigenetics,” which is a general term for heritable elements that are not DNA. Maternal cytoplasm is an example of an epigenetic factor, though there probably are more. I assume that epigenetics probably works to exaggerate genetic differences. For instance, if two lands are otherwise equal, except one population is “genetically” higher in intelligence, that population is less likely to experience a famine, and so less likely to be epigenetically stunted.
At the same time, (courtesy of Crooked Timber) Eric Turkheimer of CATO speaks carefully about “innate” differences. Eric post essentially boils down to the fact that genes are expressed differently in different environments. Thus, it’s possible to imagine a world, with the same DNA distribution, where sub-Saharan Africans outscore Jews on intelligence tests. And it’s even easier to imagine a system where the general factor of intelligence does not correlate with verbal skill, spatial skill, height, etc. Of course, those worlds are not our worlds.
Adam of The Metropolis Times emphasizes that, whatever average group differences are, and whatever their origins, people should be judged as individuals. And human rights belong to all humans, not just who score well on tests.