In regard to severity of illness, there was one instance in which all five identical quintuplets all had some signs of schizophrenia, but they all demonstrated a very different degree of the illness. There are about 100,000 genes in the human genome,and about 50,000 affect the central nervous system. We all have some vulnerabilities, but whether or not these vulnerabilities progress to disease is strongly impacted by many different life events. There is a statistical correlation between a family history of depression and the risk of developing depression. However, adequate treatment improves the risk factors.
Depression is particularly common in women of child bearing age.
For this reason, the use of antidepressants in pregnancy has been studied, and the information to date is that antidepressants are quite safe-safer that the risks associated with untreated major depression. There are databases which gather information on this subject. Effective treatment of post-partum depression in the mother helps reduce the risk of depression and other conditions developing at a later time in the child's life. In summary, there is a statistical correlation between a family history of depression, a history of depression, and an increased risk of developing depression in both the patient and their children. This risk, however, should not be overstated and should not be a reason for stigma.