Yeah, it seems to be pretty hard to tell which people are going to grow up to be alcoholics and who won't. I never had a sip of alcohol until I was 18, but I had many ridiculous drunk episodes in college and my early 20s where I passed out, threw up, embarrassed myself, etc. I think part of the problem was I was so uneducated about alcohol I didn't know what a shot was and when I made my own drinks, they were like 1/2 vodka and 1/2 cranberry juice! It took a while where I was a dummy to figure it all out and I haven't done anything close to that in 10 years. (I always thank God Facebook didn't exist when I was in college). I never drink more than 2 drinks anymore, and that is even rare.
I am sure if I ever catch my son (who is now 7) drinking a beer I will completely panic and think "that's it, he's an alcoholic!" because of his dad being one. I hope I will be more healthy by the time my son is a teenager so I will know how to handle it.