Violent games cause violent behavior is a no win position.
There are alot of very smart people working in games. But I think too many defense mechanisms kick in on this issue particularly when the argument is worded in this typical way. "Violent games cause violence" is designed to cause a bunch of wheel spinning and goings to nowhere.
I prefer to look at the influence of games in the same way as I do the influence of all mass media. There are not only opportunity costs to consuming frivolous media. There IS a learning of concepts that are of dubious value or worse. Money and guns give you dominance and power. Violence solves problems (no blowblack, no real consequences). Diplomacy has little to no value. Empathy is for sissies. Shortcuts ftw. It's not about how you play the game. Winning is all that matters. Points! High scores! The opposition is one dimensionally evil, they are dumb and they are inferior. Civility is weakness. Females are sex objects. Don't you wish your girlfriend was hot like Lara? Being and behaving in an intelligent manner is lame. Getting drunk, high or stoned is cool. Turning your brain off and learning to enjoy stupid tv/games/films is good. Get a Roku. Debate is another word for a yelling match where the last man standing wins. Torture gets results. You're not stupid, everyone else is. Stupid only counts if you're broke and powerless. If you're as unsophisticated and stupid as the bum sitting the in the gutter but you have a fat bank account, you are winning. Vice is exciting. Virtue is for idealistic morons who don't understand how the real world works. Etc, etc, etc.
The games industry will never have anything to fear reguarding the "violent games cause kids to snap" argument. It's one of those arguments that will channel us all down a pointless dead-end series of conversations. Go us.
Much of the media we consume, much of the media we make will not result in the betterment of humanity nor the world we live. That's just a fact. Indeed it has helped us all become masters of hypocrisy. Hey brother and sister, consume my mind shaping garbage but if you forget to check in with the personal responsibility region of your brain (you know, that region we were all born with) and you end up ignorant, saddled with vices, mental health issues, etc... well that's on YOU.
BLAME YOURSELF AND YOUR PARENTS because that is who I will be blaming. I had nothing to do with it. Our marketing department didn't hold a gun to your head making you buy our product even though we denied that it would cause you any harm whatsoever and even though we fought tooth and nail against legislation that would force us to label it as such. (Although if we have to, we'll settle for PG-13, R, M for Mature because they don't adequately describe the depths of the harm and the ratings board will just tally up tits and swear words which are heavily discounted because we've all seen and heard them anyway!!! WHeeeeee!) We just wanted to give you enjoyment and this is how you repaid us? Now excuse us while we brush our teeth without gazing at our own reflections in the mirror.
Alas, if only we had all eaten from a tree of knowledge of good and evil and we magically understood in the deepest sense, what made good beneficial and evil destructive. No joy. We have to teach each other.