Incest may seem “wrong”, but that’s what people said about homosexuality, too. It’s all private conduct. It is an interesting window into the sexual confusions that lie at the heart of our age.
Here is a link to an interesting article that references that exact comparison of homosexuality versus incest. Even though both views expressed in the article are not my beliefs and I don’t endore the views, it is an interesting read as it does shed a light on this topic and give a real life example.