The whole no-women-for-the-angels-to-lust-after - thing... What's with that mysterious box Cain's wife randomly fell out of? Maybe there were more of them?
Unless she WAS his sister, after all. I honestly don't know (I downright refused to read the bible in religion class), and given what kind of sites (and people)your lmtgfy-search produced I'm afraid to google it. The kind of person who writes serious entries about "facts" in the bible freaks me out way more than anything I've ever seen in THAT part of youtube. .___.