Answer to Question 1
There is a definite genetic basis for schizophrenia. The more closely related people are to someone with schizophrenia, the more likely it is that they will develop schizophrenia. For identical twins, the concordance rate is near 50. For fraternal twins, the concordance rate is about 17. Biological children of people with schizophrenia are more likely to develop schizophrenia themselves, even if the schizophrenic parent does not raise them. Biochemical factors are implicated in schizophrenia. Evidence points to abnormalities in dopamine activity in the brains of people with schizophrenia. For example, the drugs effective at treating the symptoms of schizophrenia reduce dopamine activity in the brain. There is also evidence that abnormalities in brain structures may be involved in schizophrenia. The prefrontal cortex, which is involved in organizing and planning, and the limbic system, which is involved in emotional function, are the primary suspects. Finally, there are most likely environmental influences on schizophrenia. Specifically, exposure to stressful experiences may influence whether someone who is otherwise predisposed to schizophrenia actually develops the disorder. This is supported by the diathesis-stress model.
Answer to Question 2
d
