The whole Westermarck-ian "familiarity breeds contempt" idea stands in the way of me appreciating incest fic properly -- the mystery and discovery is missing, for me. I can buy circle-jerks and this-is-how-we-do-such-and-such sorts of things as rather realistic (oh, those boys!), but start with the "oh god how I love you" and "I need you" and mouth kissing and clinging to one another in the cold cold night and it loses me.

(However, I will admit I know a young lady who wrote some twincest that knocked my socks off despite my will and better judgement -- yeah, that telepathy angle tends to help a LOT -- so I'll just keep believing that anything that can be done can be done well or abysmally, whether or not it's my "thing.")

(Also, there is Middlesex. *applause*)