Children go through phases of cognitive development. I think some people with seemingly under developed thinking abilities never progressed beyond certain stages such as concrete thinking stage. I find as a teacher that kids stuck in that phase have trouble with more abstract curricula. Doesn't mean they're not nice people though. There are sociopaths though. I believe that is genetic: my friend's son had a sociopathic father and now he's hit 13 and hasn't seen his dad for years, he developing sociopathic traits. Scary. Off topic, but scary