Your age is more significant than first apparent here I think. It means this isn't a generational thing. The mass shootings aren't a result of specific circumstances for a single generation. Or else, our two generations, having grown up watching these tradgedies, wouldn't continue to commit them. At the same time though, this isn't an 'American problem.' It's a late 20th century Amercian problem. There must have been a cultural shift in the late 1900s that produced it. I have no idea what that shift was, but there's this temporal component that I think is really important here too. Not totally connected to your point, and probably pretty obvious to you, but something I hadn't thought about too closely before. Maybe you have some idea about what the shift was.