Incest is still a repugnant transaction

Professor charged with incest with his daughter
"Political science professor xxx, 46, was charged Thursday with having a sexual relationship with his daughter, 24.

"He was arrested Wednesday morning and charged with one count of incest in the third degree at an arraignment hearing on Thursday. According to police, the relationship appears to have been consensual."

According to NY State Law:
"255.25 Incest.
A person is guilty of incest when he or she marries or engages in sexual intercourse or deviate sexual intercourse with a person whom he or she knows to be related to him or her, either legitimately or out of wedlock, as an ancestor, descendant, brother or sister of either the whole or the half blood, uncle, aunt, nephew or niece. Incest is a class E felony."

Over at Slate, there's an argument by William Saletan that even if incest is of a sort that can't lead to children (e.g. "deviate sexual intercourse"), it is repugnant because of its destruction of family relationship. His article has a particularly chilling quote:
"Read... what Woody Allen's son says about his dad: "He's my father married to my sister. That makes me his son and his brother-in-law. That is such a moral transgression. I cannot see him. I cannot have a relationship with my father …"