Well... okay, if you really want to know... Sometimes when I watch incest porn or read those stories online, I can't help but imagine what it would be like if someone in my family actually wanted me like that. It makes me feel kind of... desired and special, even though I know it's wrong. But at the same time, I don't want to push anyone away either or make them uncomfortable with their own feelings or anything.
So there you go, big brother.