No Link In the Lineage

I recently came from an AA convention where every one of the speakers told how their fathers, mothers, brothers, or sisters were alcoholics and how they believed that alcoholism was an inherited disease. Well, as they talked, I went back through my own (Irish) family. My father is eighty-five years of age and the second youngest of seven children. His brother died at age sixty-seven while plowing his garden (my dad still plows his garden), his sister died at age eighty-five, last year. The rest of his brothers and sisters are still alive. No alcoholism there.