After a few generations it really doesn't matter that much, biologically speaking. Of all the taboos on earth, this seems like the one that makes the least amount of sense. Either you procreate, or you go extinct. I don't know if there is much academic study into it due to the topic, which is again needlessly taboo, but it doesn't take a long time for a family tree to become lost in the past and people with similar ancestry to bang without knowing it. Though I'm sure it will remain the butt of jokes for a while. Or I guess the vagina of jokes since butt stuff doesn't technically count in this case.
PS- He should have gotten the 50k a day offer since he had real world experience.