Those of us who grew up like the author described, (around guns, in NRA shooting programs, etc), wonder the very same things. Im convinced that it has something to do with the drugs being prescribed to these teens.
Right after the columbine shooting, they had some woman psychologist on CNN. They asked her what she thought about the two shooters. She said "I hate to admit it, but my first thoughts were 'I wonder what meds they were on'."
That was the first and only time I ever saw, or heard from that psychologist, lol.