As long as the persons involved are consenting adults and neither of them is in a weak position (where they could be conditioned to consent), I don't think that incest should be illegal.
I don't think that the rate of incestual relationships would be much bigger if it were made legal, so I don't think that the problem of disabled children due to incest would change at all.
That said, I wouldn't compare incest to gay marriage, or mention gay relationships in any way (wtf has being gay to do with incest?) - this is because the word "incest" has a very strong negative connotation and I am sick of people mentioning gay relationships whenever something bad that has to do with sex or relationships is mentioned.
Bookmarks