It's a bit like the 'nature vs nurture' question. Does the nature of your genetics mean you can't change how you'll behave or is your behaviour purely down to how you were raised? I think in many ways those who know they are behaving badly towards others would like to blame that on the environment they were raised in, in order to absolve themselves from trying to change. I truly believe it is a combination of both, however.

This also reminds me how we will use our beliefs to justify the bad we do so we can say it is for the greater good. All of us have the capacity for both good and evil and will, at some point, do evil in our lives. We then have to choose to recognise this and change or justify and make excuses for it.