What I meant with my herd theory is that you won't do things that work against the group, like stealing from it, because there's a big risk in being found out. I think that's what morality is based on. Morality is defined by the group of people around you. It's just common sense packed into something else, and then muddled by things like religion.

Why people always try to do things like drugs, is probably because humans are very inquisitive by nature. The most used arguement for doing drugs is: "It can't hurt just to try". You want to try it out, despite people arguing against it (or because of), because you simply don't believe a lot of things you haven't seen or felt yourself.