I'm almost 35 years old. My video game collection 20 years ago - same age as these shooters - had Wolfenstein and then Doom. Later Duke Nukem 3d, Quake, and Tom Clancy. I don't play a lot of games anymore, but I have Mass Effect there as well - another shooter.
I own plenty of guns as well. I have never drawn my gun on another person.
God bless you.
Again, it’s not about individual cases, but about a collective phenomenon.
Kids learning to kill by operational conditionning without the adequate discipline provided by the Army or the Police (or even a proper family or school system).