As a Parent...esay solution...
Any PC's, Game consoles and video players under MY roof are under lock and key, and controlled by me. My kids can play with them when I SAY THEY CAN and when I've seen what it is they intend on playing \ watching....

I don't give a flying fart how old they think they are, as long as they live under my roof...its my rules.

Don't like it? get a job, move out, pay rent, buy your own *ish.....and have a ball...