Anyway. As long as I'm talking about reproduction, I really am having my doubts about this whole idea that everyone on the planet is maybe a 50th cousin. I realize that this crossed my horizon of awareness via a wikipedia article on pedigree collapse which quotes a Straight Dope column, but the sourcing seems real (a mid 1980s book by Shoumatoff, _Mountain of Names_). I've ordered a used copy so I can ascertain his reasoning more directly, but on the face of it, it seems incredibly unlikely. Cousins are "count generations back to a shared ancestor and subtract one". That sounds like less than 2000 years to a shared ancestor. I suppose he _might_ mean some idealized zero-pedigree-collapse family trees, figure the amount of genetic divergence that occurs in that time frame, and then translate that back into real family trees. And given how recently the mixing between the Americas and the EurasiaAfrica groups has been, it's just hard hard hard to believe this as a theory.
Maybe he means something else entirely by "cousin".