Personally I think genetics have to do with a lot of it. Just have you said, "If society had not totally you to murder would you have no reason not to commit it?" If you've ever thought "I should do _____" and not done it, then you know that it's not so simple. We're motivated by a complex system of desires and rationality.

Personally I would never murder someone, but that may be because I was never the type to murder someone to begin with or it may be because of the rational morality I've adopted, which is murder is bad for me when other people adopt it thus it's not universally acceptable and therefore I should not engage in it. But there's plenty more reasons to do the "right thing" than that.

Though I hate some of the societal blunders we have to resolve, I'm very glad to have an iPod, laptop, and HDTV. Take nothing for granted though.