'X breeds X and exposing someone to X will eventually desensitize them to X'. As far as I'm conscerned this is not theroy any more than the theroy of relativity, it's the 'and make them X people' bit that falls flat on it's face because of that last word; people. You know, those rational beings with actual thought processes who don't react based soley upon instinct, experiance, and stimuli because they have rationality?
Yeah, those. I mean us. Overexposure to socially deviant stimuli, such as from violent video games may well encourage deliquent behavior, but that's only with the absence of variables that discourage such deliquency such as regular basic interaction with other people. Regardless we remain sentient and rational beings for the most part and violent video games cannot be held soley responcible for any deliquent behavior.
How have violent video games effected me in particular? Well, back in my early teens, around 1993-1994, when I enrolled in karate I had no idea what I was doing, so I just mimicked my (at the time) favorite street fighter chracter's moves; Sagat, whose uncomplicated moveset at the time mixed with the basics of Goju-Ryu Karate well enough to give me one-up over my peers in sparring; I got moved to the adult class a year early. A couple years after that Street Fighter Alpha 2 was released on the SNES and I got the nickname 'demon child' as I incorperated moves from Gen's Mantis style and Akuma, while retaining the moves drilled into me in class (which resemble Makoto's).
What stopped me from persuing a professional fighting career? I was mauled by a bear in 2000 and hardly have any meat on my right arm between my elbow and shoulder.
So yes, violent video games can effect you, at least as much as any other regular stimuli.
Is that effect wholly negative? No, I don't believe it is.