I do not feel bad soley because of conditioning, much of it is inherent. People who do not have the capacity for remorse are known as sociopaths.

And be honest with yourself, if you felt no remorse over anything, what's to stop you from doing something "immoral"? You might say "because it's wrong," but why is it wrong? "Because it hurts others," okay, but why do you care? "Because I wouldn't feel right doing it," would probably be your ultimate response. Therefore, guilt is the ultimate reason for not doing most things that we consider immoral. It just feels wrong.