The correlation between suicide rate and untreated depression is almost directly proportional. Most untreated cases of depression end up translating in to suicide cases.
People commit suicide because of serious depression. Anything that can contribute to depression can contribute to a decision to suicide.
No, suicide may not be hereditary, but depression can be, which could be the cause as to why your relative may have lost their life.
Gambling is the addiction with the highest suicide rate. Ironically, it isn't even a substance, however it is just as addicting as any other substance. It is a compulsion which can cause someone to lose all of their belongings and put them into a place of hopelessness and despair, which leads to suicide in those who cannot see it through nor seek help for their problems.
They have been known to. Being a sociopath doesn't mean one doesn't experience depression. Clinical depression in sociopaths or anyone else presents a suicide danger.
a noose, pills, a blade, etc