Sorry, I didn't see your comment until right now. I can't speak to your "almost ALL acts" being "right-wingers" etc., as I don't have those statistics. Does anybody, and are they valid?
I would like to have that kind of data covering 1950-1970. "Parenting" was different before certain psychoanalytical types got rich from books about how to raise your kids. Around the '80s on, IMO. Their emphasis was putting the child on a pedistal, letting them run things, honor their wishes more than those of hard working moms and pops, forget letting them know that mom and dad rule the roost. If a couple bought into all that it lead to spoiled brats who weren't taught boundaries. Without boundaries, which we all wish had been the case as we grew up (I hated my mom for not letting me run with the wild kids, etc., later appreciated her for it), kids can't figure out their place in the world, become subject to doing their own thing, depression, drugs, etc. Of course this isn't every kid nor every parent in the world. What parents back then wouldn't have a grasp on what their kids were buying and hiding in their room? I'm imagining (though have no knowledge) a parent who would come home raging that a Black co-worker got the promotion he thought he should have gotten. Rant about it in front of an impressionable child, especially emphasizing how Blacks and "N's" are "ruining this country", well, that could have an effect if there isn't a lot of counterbalancing to it by more rational role models. To be honest I'm not up on "woke" and "right-wingers" and "left-wingers" and all those terms tossed around here, who thinks what about what.
I read now that the guy phoned or texted his dad to go into his bedroom, which the dad did, only to find the son's manifesto and other evidence of planning this terrible act. By then it was too late to stop him, but maybe at least some of it was contained.
OK, MP, enough, I am not really smart enough to know what and why, just posting what I try to make into respectful yet meaty thoughts to contribute, and I'm glad you asked me those questions.
Candy
Edited to say I don't have the type of "right wing" and other stats mentioned. Sorry, should have proof read better.