Two of my underaged cousins (one is 19, and the other is 17) were drinking beer at my dad's 60th birthday party - in full view of their parents. Their dad even helped them open beer bottles. I teased them relentlessly for drinking beer in front of their parents. Looking back at their drinking, I don't think it was a bad thing. Both of their parents are college-educated working adults. As far as I know, they don't drink excessively in front of their kids.
My parents were different in that regard. They never drank in front of my brothers and I, period (they were never really much into drinking, anyway). Underaged drinking wasn't something they overly lectured us about, since we were all pretty "clean cut" kids. I didn't start drinking *socially* until I turned 21, and I don't think my brothers did either.
I also think that providing an example of responsible drinking behavior is effective. After all, parents *are* the greatest influence in their children's lives...much more than the children would like to admit.
I would tend to agree. When I was in college, several studies were discussed in which the drinking rates of several countries and cultures were compared. Cultures in which responsible drinking was a part of the culture have lower rates of alcoholism, because children learn - as children - to drink moderately and responsibly, by watching their parents do the same - many European countries, for example, assume a moderate amount of alcohol (a glass of wine with a meal, for example) to be normal, as do some religions (Judaism has rituals which require drinking "the fruit of the vine", but any combination of wine and grape juice - including either alone - is acceptable). In constrast, many cultures ban drinking entirely, so that children don't learn to drink responsibly; people who have a drink tend to continue on to get drunk; having violated the cultural/religious taboo of drinking the first place, they drink until falling down drunk. Family stress levels and stability also tend to affect rates of alcoholism (see first article); high stress, low income, and poor stability tend to lead to more alcoholism, as parents drink to escape their troubles, and children and teens drink in imitation of their parents.