here we see some evidence that strange environments cause personality to be different. And when personality is different enough, it gets a label.
So in a homogenous and monolithic habitancy, no one stands out as odd enough to be called schizophrenic. But when looked at by a polymorphic habitancy or a demonstrative habitance, they may be considered to be a schizophrenic society.
So the criterion of how different one is from others plays a role in how abnormal one appears to others. And the criterion of having vastly different life experiences play a role in how abnormal one appears to others.