One in a hundred people have antisocial personality disorder, you probably know a few and don't know it. Most are extremely intelligent. Yes, there are so many factors on why someone snaps. Also when someone snaps, it doesn't mean they do something about it immediately, some do plot and plan.
One reason is child abuse is extremely under reported and prosecuted and goes on- generation after generation. More children have died due to child abuse in the US since Sept. 11, than all the people in the twin towers and soldiers fighting overseas. Who is fighting this war that is killing so many children and harming millions of other children (who don't die from it, but are affected?)
In Indiana alone and average of one child dies of child abuse a week. Wasn't on the news? hmmm....yeah and people wonder how something at Penn State could happen...
Some say you can't use someone's childhood to look for reasons on why people snap...well it is such a huge problem that really not very much is being done about it. There are a lot of wounded walking our streets everyday, who didn't fight in a war overseas but in the own houses growing up by people who they should have been able to trust the most. That kind of thing does impact a person for the rest of their lives.
One can heal from this, but it takes a huge amount of work.
It makes me sick when I hear people say, who saw this guy's nice home and nice looking father, he came from such a good home and neighborhood. Well child abuse happens (not to say he was abused, we don't know) in all income levels, in good neighborhoods and bad.