When I was in high school, my grandfather was arrested for drunk driving. He had gone to the local Mexican place to get dinner for him and Grandma and had had a few drinks at the cantina while he was waiting for the food. He was weaving around the road, and the police pulled him over before he got on the freeway. They tossed him in jail overnight to sober up.
Grandma called us late that night, frantic because Grandpa hadn't come home. The police called Mom, and she drove out to bail her father out.
When she came home the next day, she told me that my grandfather was an alcoholic, and had been one for as long as I've been alive.