Like you, I'm a social scientist interested in behavioral genetics. Historically, this has almost been an unforgivable "sin" to many in my field of sociology, although that seems to be slowly changing these days. Not only am I interested in behavioral genetics but I am also quite open to the idea that genes play an important role in influencing human behavior as can be seen here: http://binews.org/2011/06/opinion-genetics-the-deserving-and-the-underserving-poor/. At the same time, however, I think it's important not to overstate the case. Your use of the phrase, "the overarching reason is heredity" is the kind of statement that I worry about. I'm currently reading a very good book called Genes and Behavior by Michael Rutter. He painstakingly goes over much of the twin and adoption research and discusses the relatively high heritability figures for a number of different traits. But, at the same time, he discusses gene-environment correlations, gene-environment interactions, epigenetic mechanisms, and a host of other complexities regarding how genes affect behavior. It's difficult to read about these more complicated matters without concluding that the notion that, "the overarching reason is heredity," might be a bit hyperbolic. I did find your post interesting, though, and, applaud your efforts to integrate insights from genetics into social science.