The other thing that boggles the heck out of me with regard to incest is people who think that sex between anyone who's related at all is squicky - there's an example here (http://hokorii.livejournal.com/584882.html?style=mine) from someone who's very annoyed about a picture in which Bonnie Wright is inexplicably blurry compared to Daniel Radcliffe and Rupert Grint, and there was a storyline on 30 Rock in which the heroine was unfeasibly grossed out by discovering she was dating a man who was something like her fifth cousin.

I mean, I would have an ugh no what on earth do you think you're doing are you drunk? reaction if propositioned by a first cousin, and more distant cousins are a bit iffy if you've been seeing them at family weddings since forever, but seriously, the world's population has been rising, not falling, over the last few millenia. Do they think that they bucked the odds and managed to have all unique ancestors, all the time, since we started diverging from the bonobos, or what?