FOUR BEHAVIORAL DISORDERS THAT ARE INFLUENCED BY GENES

ALCOHOLISM  Researchers used twin and adoption studies to find that genes play a part in determining who will become alcoholic.  Environmental factors, as with many behaviors linked to genes, also are very important.  It is difficult for  researchers to pinpoint genes related to alcoholism due to the fact the illness may be caused by several different genes.  DEPRESSION  Depression is a common condition that has been linked to inherited genes, but it is also closely linked to environmental factors.  Certain events in life are thought to bring out depression.  The condition is more likely to develop if the person has inherited genes.  People can become depressed even if they have no family history of depression.  Abuse or neglect, poverty, a traumatic or extremely violent episode in a person's life and death of a parent or loved one are common environmental factors that can lead to depression.  OBESITY  A person's genes has also been linked to their chance of becoming obese.  Researchers used the methods of inheritance studies, such as investigating pairs of twins, to conclude that inherited genes contribute about 40% and the environment contributes about 60% to whether a person will become obese.  Examples of the environmental factors are exercise, social eating habits, cultural values and income level.  SCHIZOPHRENIA  This is one of the most serious disorders that is linked to a person's genes.  A strong link has been shown in many studies between schizophrenia and heredity.  If one of a set of identical twins has the disorder, there is a 46% chance that the other twin will show symptoms.  Other children with a 46% chance of having the disorder are children who have both parents with schizophrenia.  There is only a 1% chance that people will develop this disorder if they came from families where no on has it.  Environment does play a role in the development of schizophrenia.  There is an 11% chance of showing schizophrenia, if child is adopted into a family in which one of the adopted parents have the disorder. This can happen even if the child's birth mother does not have it.