You know, it is silly to deny that video games can exacerbate violent inclinations in particular individuals. There are people who are by nature prone to alcoholism, so if you subject them to alcohol over and over what kind of result would you expect? I for one can say that Nintendo games of the 90s have really harmed my psyche, as I would get really frustrated with them, but couldn't stop, so addictive they were. Of course, the problem is that all sorts of things can exacerbate schizophrenia in certain individuals, so we might as well ban every piece of entertainment.
It mostly boils down to parental control. If parents don't know their own child, what else can be said?