I don't totally agree with the video game angle
IMO it has as much to do with lack of parenting as anything
Hell I played "violent" video games as a youngster all the way up through my early twenties
They were entertaining but ive never fekt rhe urge to go on a killing spree, I was raised by good parents who instilled values allnd morals,
Were you on psychotropic medications during those times?
You also say "parents", as in "two". That is another difference between you and the shooters.