I think you are really looking at the wrong problem. Yes, those things you mentioned can have some influence but really think about it. I grew up in the 1960's. We had GI Joe, all sorts of play guns made out of plastic, BB rifles were very common, even then. Then, on the nightly news, we had TV coverage of the Vietnam War and other Wars raging around the world. You saw blood and guts there. There were many movies, even then, that were violent.
The difference was we were grounded in certain values and we knew right from wrong. We believed in America even with the Kennedy Bros being assasinated along with MLK. We put a man on the moon. We were America and the future still looked bright.
We have all sorts of electronic gizmos today,