It seemed rude to me, because it came across as if you couldn't be bothered to absorb any of the info I had given, just because I didn't give an answer like everyone else was. No, I don't know about all that scientific/genetic mumbo jumbo, but I still have my opinions on the morality of the subject; I've a read a few stories and heard of a few incidents that others haven't mentioned, so I think I deserved to have my say.
As for other types of incest, I think the same applies to all family members. Family should be people you protect and provide support for, or look up to for guidance and stability, not people you f#ck around with. Whatever the blood relation, it's still abusing your power and position as a family member. I used the parent/child example, because I think that is the worst form of incest, but the same could be said towards people abusing their siblings, cousins or any other relative.