Schizophrenia is a no-fault, equal-opportunity illness most likely caused
by a number of factors, both genetic and environmental. Most scientists now
accept a two-hit theory for the cause of schizophrenia, which suggests that
the genetic susceptibility is compounded by one or more environmental
factors:
-Genetic susceptibility: Based on family genetic history, some people are
more vulnerable to the disorder than other people are.
- Environmental factors: In someone genetically predisposed, certain
environment factors may come into play, such as:
• Physical trauma that occurs to the fetus during childbirth
• Oxygen-deprivation or some psychological or physical problem
that occurs to the mother during pregnancy and affects the developing
fetus
• Emotional stress, such as the loss of a parent or loved one during
young adulthood
Although schizophrenia is genetically influenced, more than genetics is
involved in its development. Studies of identical twins show that, if one twin
develops schizophrenia, the other twin has only a 40 percent to 50 percent
chance of also developing the illness. There’s also an increased risk among
fraternal twins when one develops schizophrenia, the other has between a 10
percent and 17 percent chance, far less than that of identical twins. Having a
parent with schizophrenia also increases a person’s risk of developing the
disease, to about 10 percent. And if you have a sibling with the disorder —
not your twin — you have a 6 percent to 9 percent chance of developing the
disorder yourself.
Scientists still don’t know the precise causes of schizophrenia for any particular
individual, yet family members and patients themselves tend to dwell on
(or even obsess about) finding a “reason” or a “cause” for the illness.
Although this instinct is a natural one, finding the precise cause or explanation
is impossible, not to mention counterproductive — finding a reason
doesn’t help treatment, and it often creates unnecessary and misplaced guilt,
with one family member blaming another
