A study released Thursday by the Substance Abuse and Mental Health Services Administration has news that shouldn't surprise any of us: kids who engage in underage drinking most often get their booze from adults, typically their own parents or their friends' parents.

The study consisted of a random sample of 158,000 kids aged 12 to 20 who were questioned about their drinking behaviors. Researchers found that 40 percent of teens reported receiving alcohol for free from an adult in the past 30 days, and that one in 16 got the drinks from a parent or guardian, while one in four said the provider was an unrelated adult. One in 12 were being served by an adult family member who was not their parent.

And of course, some kids -- about four percent -- reported that they simply helped themselves to alcohol in their homes.

Surgeon General Steven K. Galson holds the grown ups responsible for all this underage drinking. "In far too many instances parents directly enable their children's underage drinking -- in essence encouraging them to risk their health and well-being," he says. "Proper parental guidance alone may not be the complete solution to this devastating public health problem -- but it is a critical part."

What makes a few kids swiping some beers from the garage fridge a "devastating public health problem?" How about this: one out of five kids surveyed said that they had taken part in binge drinking during the previous month. A binge is defined as consuming five or more drinks on one occasion. Half of kids participating in the survey reported drinking in someone else's home, while a third said they were drinking in their own houses; a smaller number, less than ten percent, were in a bar or club.

What can you do to keep your kids from becoming a statistic? Model good drinking behavior at home, for starters. Know your children's friends and their parents. And don't be afraid to say no and stick to it.