Hehehehe. Love a controversial title and this is a controversial title. But you've made the case well. I try and rationalise these things as best I can - and to behave like a rational human.

If two consenting adults wish to engage in a relationship then it is no business of mine to interfere with that relationship with the caveat the relationship does no harm to others. Once we have removed the chance of children, and to a lesser extent the shame of parents - then I don't think there's a valid argument for state interference. It should be a matter for the couple to decide. Your case for incest stands. Moral repugnancy alone should not create a case for active interference by the state or any other party.

And I've got a new book to read. :o)