Agree with DD. On my psych rotation in the state hospital (sickest of the mentally ill patients), I learned it can be triggered by a stressor and many suffered horrendous abuse as children. Not something they're necessarily born with (though there is certainly a genetic component), all sorts of environmental factors come into play. Many of our schizophrenic patients had perfectly normal seeming lives, then some stressor caused a psychotic break. It can come on gradually or happen suddenly.
