The tendency toward suicide is inherited and passed from generation to generation. The suicidal person wants to die and feels that there is no turning back.
All suicidal people are deeply depressed.
Although depression is often closely associated with suicidal feelings, not all people who kill themselves are obviously depressed. Also, people who are extremely depressed usually do not have the energy to kill themselves. There is no correlation between alcoholism and suicide. Alcoholics are prodded to suicidal behavior and even people who don't normally drink will often ingest alcohol shortly before killing themselves. Suicidal people are mentally ill.