My personal experience leads me to strongly believe that people can be mentally ill without having been abused, the same way they can be born blind or deaf or with any other disability.
Sup man, hope you're okay.
Modern science of mental health and neurology says otherwise -- in the vast majority if not all cases of mental illness (exception made for provable congenital defects affecting the brain), there is always an environmental trigger associated. This is why there isn't a "schizophrenia gene" or a "psychopathy gene", but rather genes that make people
propense to schizophrenia or psychopathy.
If you are interested in the topic, I suggest these conversation starters:
http://fdrurl.com/bibhttp://www.youtube.com/watch?v=eOScYBwMyAA <- this one in particular
http://reason.com/blog/2010/08/19/reasontv-three-ingredients-for <- famous neurologist
Stef has a few interviews with (inb4 "fringe!") well-known mental health professionals about the topic. I suggest you take a look at these too.
Please do ignore the two other people in this thread -- they are attempting to sabotage this post by either provoking me or derailing the topic. Some people just have virulent and abusive reactions to discussing the (pretty much taboo) topic of child abuse; I won't speculate as to why they do that, but you can see for yourself that they
definitely do, right here.
The current research is that schizophrenia is caused part genetic and part behavioural reasons. Proved by the reasons that mental health problems can be heritable and by the fact when identical twins are born and one develops schizophrenia. That the other twin is only 50:50 likely to develop schizophrenia as well.