I think it depends on the person. Some people are more easily influenced than others. The biggest influence on children is probably their friends. My brother for example, even if he believed in God, would probably never admit it for fear of what his friends would think. He goes out with his friends and gets incredibly drunk. They get into fights. They get hurt. Do they enjoy this? In a way, yes. But only because it makes them popular with one another. Why is it 'cool' to have fights with other people? Is it the media? Or is it just the 'dominance' instinct and looking 'macho'?
My brother and I have been brought up the same way, by the same person. We have both played violent computer games and seen violent films. He listens to rap music and I'm partial to the occasional bit of heavy metal, as long as the lyrics aren't too disturbing.
However, he likes to 'go out and have a good time', get totally wasted, live for today and just party. I, on the other hand, whilst I'm not opposed to having a good time, would rather do it without alcohol (I like dancing!). I don't 'live for today' as such. I don't want to go out and 'get in with loads of boys'.
How do we explain such differences in two people who have been brought up in exactly the same home environment? Is it based on our characters and personalities? Or is it our (very different) groups of friends? Or perhaps the friends we choose are based upon our personalities?