It's the classic argument of nature versus nurture. Is schizophrenia a genetic disorder that's inherited through complex processes, or is it simply caused by the environment one grew up in? The simple answer is both.
Economics
According to Brian H. Shirts (2004), schizophrenia is estimated to be 70 percent to 90 percent hereditary, leaving 10 percent to 30 percent to environmental causes. The latter leads one to wonder what in the environment brings someone to such a state. The American Journal of Psychiatry (Social Adversity, 2005) notes that cases of schizophrenia are more prevalent in ghettos and social slums in the world--as much as 2.7 times more. So apparently, lack of money and the pressures they cause can lead to schizophrenia.
Education
Schizophrenia has no known cure and can't be fully prevented. Someone who would normally develop schizophrenia develops it in due time. However, the severity of schizophrenia can be reduced heavily by preventive intervention if caught early enough. That said, a person would have to know that she's at high risk for schizophrenia--having been educated in early symptoms and having a knowledge of family history--before seeking preventive care.
Stressors
In a debate on the social environment of schizophrenia as a cause (BjPsych, 2003), both parties agreed that stress could either cause schizophrenia on its own or bring a relapse.
