I remember playing DOOM on the computer with my cousin once when we were pretty young. We were saying something along the lines of if this ever really happened, how we'd stick together. My dad walked by and said, "You know this isn't real right?" I didn't even know how to respond to him because I thought it was such a stupid question. We weren't having a conversation about the possibility of shotgunning monsters in the face in a dark building, we were confirming each other's loyalty to each other through times thick and thin. My dad just happened to be walking by and mistook a very healthy conversation, as an unhealthy one.
I was old enough to drive when Grand Theft Auto came out. I remember my friends making comments about the adjustment from driving around carjacking, crashing into things, and running down prostitutes, to getting into your own car to drive home. I remember that it was completely unheard of to be able to negatively interact with a life like character over and over and over (stomping a body around after you already killed it), and it was disturbing at first, but I adapted to it and accepted it as part of the game. It is what you do while playing the game. I can say the same thing about joining committees at work. I'd rather not, but it is part of the corporate dance that you do to get promotions.
I bring all this up to share that around the time GTA came out, was when I decided to buy a Corn snake from the pet store. More than any video game I ever played, more than any of the
horrible things I watched on Ogrish when those sites were popular, what really had the greatest affect on me was having to kill mice for my snake. Sometimes I would let the snake do the work, and while it was awesome to behold, it wasn't any more comfortable to watch. I had that snake for almost four years, and killed a lot of mice. I got used to it, but I never enjoyed it.
I guess the conclusion to this long post is that movies, books, videos, and video games are just what they are, and not usually any more. People tend to forget that along with video games, kids are still experiencing real life at the same time. They experience real life death of family members, kids at school, and their pets. The experiences of real life will always outweigh those of entertainment media. If you have a kid that doesn't blink an eye when Fido or grandma dies, then you may look into getting some kind of evaluation done. Chances are, if someone has a mental condition, it was there all along and wasn't dependent on whether they played video games or not.