I think it would be interesting to do a poll here, though of course, like all internet polls, it would have to be taken with a grain of salt.
Personally, I think brothers doing it is hot as hell, though I'd never consider it with my own. That is so gross. Strangely enough, twins don't do much for me. I suspect it's the Romeo-and-Juliet quality rather than the have-sex-with-yourself fetish around brothers which turns me on. I'm a romantic all the way.
Speaking of which, I actually have a
short film called "
Starcrossed", which deals with this subject matter in exactly this way. Two straight-acting brothers find themselves falling in love, with tragic consequences. I may upload it shortly. The imdb link is:
http://www.imdb.com/title/tt0420931/
"Darren and Connor are two star-crossed lovers bound together by blood. Set in a suburban neighborhood, Star-crossed is an atmospheric story of two brothers who's relationship develops into something more than society could ever handle. Unable to deny their feelings for each other the two brothers try to hide their relationship from an unkind world but fail. The boys decide that a world that cant understand them is a world thats not for them."
I'm hoping it might break through to some of bigotry that ironically infest this thread, though if the gay rights movement has taught us anything, it's that it sure ain't easy.
It's also been treated in a lighter way in this comedic commercial:
http://www.youtube.com/watch?v=V9WAMo40qnA
Incidentally, it's interesting how an issue is defined effects the dialogue around it. While this thread was labelled "Weird" by the initial poster, an older thread titled "Twins and Brothers", was labelled "Fetish", and had a considerably less hostile environment than this one. I find it similar to labelling homosexuality under the column "deviant", versus under the column "alternative".