I think really the age limit should be 18- but on the way there are all sorts hurdles.
Y'see- most kids once they hit 18 or even 16 haven't been allowed to drink- they don't know thier limits and how much they can have- so they hit the piss hard- they wind up doing dumb things they know they will regret.
However- if at about 14 the childrens parents slowly introduce them to alcahol- say 1 glass every Saturday night then it is a lot healthier- and as they reach about 16 then let them enjoy alcahol in a a safe, supervised enviroment- hence when they leave home for University or even turn 18 they know thier limits
Thats what my parents did with me- and guess what- it worked extremely well