More of us can't quit; One in five adults has a close relative addicted to drugs or alcohol, says a poll that suggests families pay heavy price.(Main)

Byline: RITA RUBIN USA Today

If not for his wife and four children, Tim Ryan says matter-of-factly, he'd be dead.

Ryan, 37, estimates he has been sober, on and off, for eight of the past 16 years. He says his most recent stint began about six months ago, when he stopped drinking and using heroin. This time, he says, sobriety is going to stick.

"I spend a majority of my time with my kids," says Ryan, a partner in a Chicago information technology company who often works from his suburban home. "I look at their eyes and their faces. If I can't quit for them, I've got a problem."

Addiction is endemic in American families. A USA Today-HBO …