In Evolutionary theory, Population Generics typically assumes random mating. But because of both assortative mating AND a secular trend toward geographical re-distribution across political, social, and economic factors (bankers in NY, techies in SF, etc) you have the potential makings of speciation: Homo Fund Manager, Homo Engineer? And which proto-species who would the first Mars colonists likely come from? Will a long family of engineers shun a potential husband because he stems from a long family of bankers?