I've been a gamer all my life, and I'm very defensive of my pastime. I certainly don't believe that banning games will solve any issues, especially when there are other forms of violent media. I do however also see the merit in the work of Albert Bandura, who was a cognitive theorist. In his studies, children who were exposed to staged scenes and images of violence, replayed those actions on their toys.
I work with children. Some of them have mental deficiencies. One boy, Adam has had obvious exposure to violent games/ movies. He has threatened his teacher on a few occasion, to cut her head off, or set her on fire, and shoot her. He is only 6 years old. He is constantly in trouble for biting, punching, kicking, verbally abusing and making death threats against other children. Where does a 6 year old learn to threaten cutting someone's head off?
I'd argue that a sane person will not re-enact things that they see, and observe in a game or movie. Unfortunately some people are not 'all there'. I dread to think what Adam might be capable of in a few years, as he is one that cannot identify that what he is doing is wrong.