There are some mental illnesses that seem to run in families and it is possible that if one family member had an illness that led to suicide another member may also have that same illness. However having the same illness does not mean that both persons will commit suicide. The life circumstances of each person will differ and the decision is up to each. There is no reason to believe that a person is predisposed to suicide because he or she shares the same illness as a family member who did commit suicide.