Heritability and Its Estimation, Especially in Humans

03 Sep 2019 22:38

I shan't repeat myself.

One issue which I have never really seen adequately dealt with is that human behavior could be substantially predicted from genetics even if no genetic variants have any causal impact on behavior. All that one would need to create this would be for (1) behavior patterns to be shaped by culturally transmitted habits and traditions, which are (2) largely transmitted through families and social classes, which turn are (3) largely endogamous. Endogamy will create population structure (in the genetic sense), which in turn will correlate with traditions, and so behavior. Twin designs won't handle this, unless separated twins were really assigned to completely random cultural backgrounds. (Even then, you'd also need to assume that other people pass on traditions to the randomly-placed twins in ways independent of their genetics and the phenotypic expression thereof.)

See also: Historical Genetics