Yes, I agree. I never remember hearing about mass shootings until about the last 30-35 years ago or so. They are a pretty recent phenomenon. And they are mainly committed by young men. Sure, sure there are some that are by a different age group, but it's striking how often it is committed by a young man. We had better start committing time and resources into finding out what is happening with them.
I agree that these violent video games could be a part of it. It boggles my mind how parents allow their kids to be playing with these video games for hours every day. That is lazy parenting. Some other things that pop into my mind are anti-depressants, drugs both legal and not, our food supply, what are these kids eating now? Family units have changed. These kids are being raised totally differently than our generation. Our society has changed trememdously in the last few decades. Obviously not for the better in a lot of ways.