What you've you are two problems. One is that the media onslaught portrays very real violence. The other is that in our world of perpetual childhood, many reach adult hood without ever being able to distinguish fantasy from reality, thus their real world is an extension of the fantasy environment. I would think mind-altering meds play into this inability to make the distinction.
These are all my observations of the situation, not based on a study or anything like that.
I’ve always followed the philosophy that it really omes down to parenting and the concept of responsibility/action/consequenses.
I can respect that others are opposed to violent games as a whole. Personally I think they are little different from violent literature considered classics. Once in the mind, the imagination makes them equally ‘real’ so to speak. But no one is opposes to Shakespeare despite the sex, death and Machiavellian plotting.
Consider:
One kid goes out, gets a copy of Grand Theft Auto, blows away half of Miami/NYC and then tries it out for real.
Another finishes GTA and heads down to Gamestop for the latest release of Battlefield.
The difference is that one never got taught right from wrong/actions have consequences/ fantasy and reality.
Parenting.
The same applies to Freddy Kruger, Jason or even the patheticness that was SAW.In fact millions upon millions of kids world wide never act out the violence of games or movies. Which leads to the above. Parenting.
Whether ‘allowing’ kids access is another thing entirely. I went by whatever my daughter was ready to deal with at any given level of development. For me and her at least, it worked out fine.
As with most things, parents who actually pay attention to their kids don’t often end up with psychos. Sure, there are exceptions. But almost invariably you have a kid there with a genuine mental issue that no amount of attention can overcome.