I suppose I can understand it a bit more if its one of those havent seen each other ever things when they meet and start sleeping together without knowing about it, as it isnt their fault, they didnt know(I would imagine that kind of thing is pretty rare though)...but to knowingly sleep with a member of your family is just gross.

medically there are good reasons for not doing this and psychologically there are also many good reasons.

Whilst the Bible recorded it as reality it is naturally dead set against it and rightly so.

Wow. What the hell has this world got to. People are going to start marrying there children and nieces soon.