How does genetics affect schizophrenia?

Im doing a Highschool Graduation project on this topic, please leave some good advice.

a genetic component to schizophrenia has been suggested, but definitive research hasn't found much (a particular gene). It's more of a suggestive finding than definitive, since the only evidence we have for a genetic component to the disease is that it runs in families.

There is a known link between parents and grandparents that have schizophrenia and the disease developing in the children. There is no direct evidence that a person will become schizophrenic based on the parents disorder. Essentially, you have an increased probablity of developing. There is alot of debate over this right now in the medical community because of the uncertainty.

The major problem is that some people develop schizophrenia that have no genetic disposition (that is none of the parents or grandparents have the disease), and there are people who are born to schizophrenic parents/grandparents that never show signs of the disease.

Thus we're stuck at a sort of nurture versus nature type of argument on the disorder. In my professional experience I would say that most children of schizophrenics develop one or more mental illnesses while passing through puberty. This can range from S.A.D to manic depression to eating disorders. Though I can't say with any certainty that its the genetic disposition that causes this problem over the fact that most of these children grow up in a hostile environment. An unfortunate side effect of having a schizophrenic parent.

Some other controversial believed causes include: high stress life (PTSD), childhood trauma/abuse, head trauma, and drug abuse (particularly, very frequent use of LSD).

I hope that offers some help, there are a plethora of books on beginning psychology that explain the condition.