Nature, Nurture and Madness/Psychosis.
from an essay by Oliver James
published in the Guardian, 22 October 2005,

"... The fact that some two-thirds of people diagnosed as schizophrenic have suffered physical or sexual abuse is shown to be a major, if not the major, cause of the illness. Proving the connection between the symptoms of post-taumatic stress disorder and schiziphrenia, Read shows that many schizophrenic symptoms are directly caused by trauma. ...
    " ... it is not being suggested that all cases are caused by parental care. ...
    " ...40 studies that reveal childhood or adulthood sexual or physical abuse in the history of the majority of psychiatric patients...   A review of 13 studies of schuizophrenia found rates varying from 51% at the lowest to 97% at the highest
    "Among the sexually abused there is a greater risk of developing schizophrenia the earlier the abuse happened, the closer the relation to the abuser and the more invasive the act. Of course, not all schizophenics suffered trauma and not all abused people develop the illness. James speculates that genetics and less overtly cruel early childhood maltreatment may be involved in determining outcomes. ... negative or confusing early care may be an important addition to abuse as a cause.
    Mother are crucial in early nurturing... Children with schizophrenic mothers are twice as likely to develop the illness as those with afflicted fathers. This could be because disturbing mothers are a major factor. Equally, it could be due to gender-linked genetic inheritance, but there are strong reasons to doubt it. For instance, the mothers of 11,000 Finns were asked if they had considered an abortion for their child during pregnancy, a clear sign that the child was unwanted, increrasing the likelihood of subsequent maternal deprivation. Following up 28 years later, the offspring of mothers who sought abortions were four times more likely to be schizophrenic..." (Compare also Lowen's of "Bioenergetic" who postulated that psychosis is due to intrauterine rejection!)
     " ... the more negative and mystifying the parents had been in a son's childhood, the greater his likelihood of being schizophrenic...
    "Fifty-six children born to schizophrenic mothers who had subsequently been adopted at a young age ... On its own, simply having a greater genetic risk ... did not incease the likelihood... However, if there was a high genetic risk and it was combined with mystifying care during upbringing, the likeihood was greater."

Stress in general is also implicated. The poor are much more likely than the rich to get ill.
   Furthermore "... if you become ill in a developing nation where hardly anyone is treated with drugs, you are 10 times less likely to have any recurrence of the illness...

This view comes out of the work of John Read (and his associates) and was published in Acta Psychiatrica Scandinavica and in his book Models of Madness.