As a kid, I got to watch whatever, play whatever game (mind you we didn't have anything "that" violent back then) etc, and I turned out fine. Hell, I went to a theater to go see Roboocp with my mom when I was 9, blood splatting, curse words flying, people dying left & right, the ED 209, tities in the locker room, etc. And you know what? It was a farting awesome movie. Did I go out and kill a cop, turn him into a Robot, try to take over a coorperation, snort lines of coke off of hookers, etc? No, I just enjoyed an awesome movie for what it was. I also saw Terminator when I was 5, didn't go and try to start the robot apocolypse either. I'm sure you get the point.
Normal kids don't have reactions from violent games, its the crazy shits who would kill people anyway. Go do manditory psychological tests in schools, and leave the rest of us alone.