One thing that is proven is the link between genetics and depression. For those that grows up in a single parent family where the Parent is an abusive alcoholic and bipolar, the outlook can be a little glum. All siblings (three) have varying degrees of depression. Of four, I was the only one that took up the drink. Being a black sheep I joined the Army to cut myself from the family and "become a man". I found alcohol helped me fit in and be accepted in an elite regiment. I was otherwise a small and skinny reserved pimply faced 18 year old. Three years later I was a cynical and aggressive veteran of overseas duty with an alcohol problem and nose for trouble that eventually got me kicked out. That love/hate affair with booze lasted 25 years. In the meantime one of my siblings committed suicide and my old man, estranged for 25 years, died a lonely skid row drunk. The other two siblings battled depression over the years and are now generally happy. So which came first? I'd say I inherited a mental illness from my father that later expressed itself in alcoholism and other addictive behavior patterns. Grace of God I survived it.