Question: Is There A Genetic Predisposition To Mental Illness? I am in the process of making a decision as to whether or not I will have a  family. My mother suffers from clinical depression which was also the case of her two brothers (my uncles). My sister suffers from Manic Depression and  I have suffered a nervous breakdown at the age of 23 (now I am 40) with a depression for 2 years. After a lot of effort I managed to get out of it, attended university and now have a successful career. Over the years I have suffered from bouts of depression associated mainly with stress at work and I managed to overcome them without a medication. Seeing my family, including myself suffering all these years, I am hesitant to have a family since I have heard that such diseases can be hereditary. Answer: I would like to comment on three major areas. Usually disease is not inherited. Instead, vulnerability to disease is inherited. There are many effective treatments for depression, and intensive research further improves the hope for additional more effective and better tolerated treatments in the future. Details should be discussed with your physician. Many traits, such as red hair, blue eyes, and some facets of our personality and temperament are inherited, but most disease is not inherited. A few exceptions are diseases associated with a genetic defect such as-hemophilia, Huntington's, Tay-Sach's, Gaucher's, etc. The significance of genes is apparent when we see that identical twins often demonstrate similar personality traits. For example, one set separated since birth had very different developmental backgrounds. One was raised Jewish in Africa, while the other was raised in the Nazi Youth Movement. Although they never met, they both wore rubber bands on their wrist, and both enjoyed scaring people by sneezing in elevators. There are many other similar examples demonstrating the significance of genes in determining many facets of personality.  In contrast, however, most diseases do not show a 100% correlation in identical twins, or the disease may be present in a very different degree of severity. There is not a 100% concordance for depression in identical twins. 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. It is important to point out that your children would have only 50% of your genes. In addition to genetics, if someone has a history of one prior depression, there is a 50% risk of a second depression. With two depressions, the risk of a third is 70%. With three, the risk is 90%. However, adequate treatment improves the risk factors. About 17% of the population suffers from depression at some point in their life, and one large study demonstrated that 48% of the population suffers from some form of mental illness at some point in their life. 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. If there is a significant history of depression, PMS, and/or family history of depression, a greater alertness to the possibility of depression and post-partum depression is needed. 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. An awareness of the risk, appropriate vigilance, preventive strategies, and early effective treatment if depression does occur improves the prognosis for both you and your children. A risk of depression, alone should not be a reason not to have children. The details and specific strategies should be discussed confidentially with your personal physician. Robert C Bransfield MD   The diagnosis and treatment of any medical and / or psychiatric disorders requires trained medical professionals. The information provided is to be used for educational purposes only. It should not be used as a substitute for seeking professional care for the diagnosis and / or treatment for any medical and / or psychiatric disorder.