The Kinship Effect
I have done a lot of genealogical research — that’s family history stuff for those of you who don’t like big words — and noticed that most people know the details about their parents and grand-parents, but few can go further back than that. Now a study out of Iceland gives some explanation for this social phenomena — it is better to marry your third cousins! (Biologically speaking, that is.)
Don’t believe me? You can read the study here. Third cousins who marry have more children and grandchildren than those more distantly related. In small communities, if you can manage to forget who your great-grandparents were, you can enjoy the fiction that the third-cousin you just met is not related to you.