Oddly, I saw this Science Daily article cited in support of the absurd ‘ethnics/races are purely social constructs’ meme. Odd because…”No Such Thing As Ethnic Groups, Genetically Speaking” should read ‘Some Central Asian groups are relatively more genetically self-segregating.’ (Not exactly the case to prove the above point)
As for that liberalese “gotcha!” — Compare:
“No Such Thing As Ethnic Groups, Genetically Speaking, Researchers Say”
ScienceDaily (Sep. 1, 2009) — Central Asian ethnic groups are more defined by societal rules than ancestry. Researchers writing in the open access journal BMC Genetics found that overall there are more genetic differences within ethnic groups than between them, indicating that separate ‘ethnic groups’ exist in the mind more than the blood…..The boundaries used by individuals to distinguish themselves from members of other ethnic groups are generally cultural, linguistic, economic, religious and political.”
And the actual article:
“Since the work of Frederik Barth in the 1970s  anthropologists have placed emphasis not only on presumed common ancestry and shared cultural traits, but also on the “boundaries” used by individuals in order to distinguish themselves from members of other ethnic groups. These boundaries can take different forms – racial, cultural, linguistic, economic, religious, and political – and may be more or less porous. The persistence of such boundaries implies rules. One of the most common rules around the world is an endogamous preference for mate choice. In conclusion, our analysis of uniparental markers lends support to Barth’s hypothesis by indicating that ethnicity, at least for two (and marginally three) of the Turkic groups in Central Asia, should be seen as a constructed social system maintaining genetic boundaries with other ethnic groups rather than the outcome of common genetic ancestry. It further highlights the differences between Turkic and Indo-Iranian populations in their sex-specific differentiation and shows good congruence with anthropological data.” (Heyer, et. al., 2009. Genetic diversity and the emergence of ethnic groups in Central
Just wait till Transhumanism gets off the ground. Assuming some degree of group competition, we’ll see how long the Cultural Marxists remain liberal.
That said, assortative mating is actually quite common, as shown by Risch et al. (2009) in Ancestry-related assortative mating in Latino populations