I'm going to re-post what I originally put in your other thread, AOG, because the same applies:
"There is absolutely no evidence whatsoever that violent video games have *anything* to do with violent behaviour. At all.
Olson & Kutner, two psychologists at Harvard University, assessed the evidence available. They consulted neuroscientists about the supposed evidence of brain stimulation, they conducted polls on the usage of video games, they conducted research into teen violence. They found no relationship whatsoever between violent behaviour and violent media. None.
As a young person - a member of the first generation which can plausibly call itself lifelong users of the internet and of videogames - I am sick of people who have no idea what they are talking about making badly-informed speculations about the supposed effects of video games on their consumers. It can't be justified anecdotally, or by any substantive, well-scrutinised research of any kind. I would hazard a guess that at least half the ABers who blame video games for this kind of revolting act have never picked up a controller.
Do not presume to lay this atrocity at the door of the video games industry."