My eldest son has been playing the Grand Theft Auto games (and lots of other of that type of game) for a looooong time now.
While he is now an adult he's been playing them since his middle teens.
We live on one of the largest housing estates in Europe, and as such has a "bad" reputation for
teenage crime etc.
Despite this, and playing the games a lot he has never been tempted to hotwire and steal a car, tool up with Uzi's
and go out shooting and raping, innocent people and prostitutes, or gunning down druglords and taking over their
criminal empires.
Why ???
Because most kids understand the difference between video and reality.
Personally I don't like those types of games (Don't get me wrong I love a good FPS)
but I think any kid who gets sucked into a life of crime and violence soley on the influence of video games
has to be very suggestible and will probably have underlying mental problems.
If your kid is a normal healthy, youngster, I wouldn't worry too much.
However I would still monitor the type of games he's playing as they tend to have a LOT of swearing and bad language
and THIS they can and probably WILL pick up on and repeat in the playground and around their mates.