Caveman boogie

Why is it that I feel sick when I see scat (not the type of singing)? The thought doesn't sicken me. In fact there isn't a thought I can think of that sickens me come to think of it. But seeing it make me wretch.

My theory? It's because I know it's wrong. Now for the important bit. Is it a social or an instinctual reflex? If it's socially programmed in then it's because I've been told that it's wrong and my subconscious is making sure that I remember that fact.

If it's instinctual, could this explain other things? Could this explain how cavemen figured out sex? I'm guessing they didn't have the patience for trial and error. Are you pre-programmed with the knowledge that this is right and that is wrong? That things shouldn't go places that have no benefit? I'm sure it's something we can scientifically prove/disprove....I just don't want to.