Ed, as you will become aware (although with girls it's less of a problem until they're teens) it's almost impossible to keep your kids out of bad company, unless you lock them in the house 24/7. Believe it or not I do have some rules
and I've tried to keep games/films/music/tv that I consider unsuitable away from my kids. Unf especially with boys, if you ban them from something but their m8s have it, they'll get their mitts on it anyway. I've given up on the violence side; and other parents I speak to say much the same thing, it's so much a part of games that it's impossible to police. And the GTAs and Resident Evils are mixed in with Spyro, Pokemon, Mario, Sonic, stuff like that. When I was a kid I used to go setting fire to garages and smashing up building sites and derelict houses, making firebombs etc. Now I know my nipper ain't doing that, so do I have a right to complain because he indulges in cartoon violence GTA-stylee? If I'd kept me ban in place, he'd just be playing it round his m8s anyway and exposed to god knows what else; at least at home I know what he's doing.
(girls only become a problem when they discover boys; before that they're as good as gold)