One thing is the official age limit. Another, and much more important thing, is the age when the parents start serving alcohol to their children.

My parents allowed me to have a small sips starting when I was 5. At that point in my life, I could not understand why adults wanted to drink such awful stuff when there was sweet soda. My parents have never said NO to me when I asked for alcohol.

Result? I learned that alcohol is something you drink in moderation, I've never been (really) drunk, I've never associated alcohol with rebellion or a necessity for having fun or having a diner.

You also have to take into account that alcohol affects people differently. Some people just get tired, some people feel really good.

Also, some people have addictive personalities (in addition to alcoholism).

I am not sure how you take away "alcohol is something you drink in moderation" from being given it at an early age.

Because you learn that its just another beverage rather than some forbidden fruit.

To go even further, it's just another beverage that tastes nasty. As a kid, my mom and dad let me taste a variety of beers/wines from time to time when I asked, and every time I thought it was disgusting. I still don't drink primarily because even years later I cannot stand the taste of alcohol, even when it's diluted; my secondary reason is because I don't want to limit my experience of life.