If anything, I absolutely support children experiencing alcohol with their parents relatively early on.
My daughter came home crying one day when she was 13, because the other girls at school had been bullying her about not knowing what various alcoholic drinks were. I ordered pizza, then went to the shop next door and bought one of every kind of booze I could for about £50 (we didn't have anything in the house anyway) so she could try them all and figure out what she did/didn't like. Obviously, I made sure that she wasn't getting absolutely blotto, and there were plenty of breaks for food etc - it was about trying it, and experiencing the feeling of getting merry.
OH and in-laws were absolutely horrified and convinced that I was turning her into an alcoholic.
But...do you know what? She liked a few of the drinks, but woke up with a bit of a hangover the next day and decided she didn't want anything to do with alcohol. She didn't touch another drop until she was 18, even when offered, and she very rarely gets drunk (she's 29 now) compared with all of her friends who're out getting blasted every Friday and Saturday night.
When the girls at school found out, they stopped needling her about it because she'd tried everything. It also had the effect of making us the coolest parents in school, which weirdly made her more popular (I'll never understand teenagers).
My grandfather was Italian, and so the idea of not drinking wine with dinner was completely alien to him - that was basically my inspiration. He insisted that my cousin and I (same age) had "a bit of wine" with Sunday dinner from the age of about 12. Of course, being Italian, "a bit" meant he was making a concession that it should only be half a pint of wine...our parents always had to sleep it off before driving home, and we never managed to finish the glass...which was another good lesson for us: you don't have to finish every drink that's in front of you. Stop when it stops feeling good.
Point is, if it's maturely handled by the family in question (rather than the prohibition-era thinking that leads to it being a taboo), then drinking earlier than 18 can actually be an educational experience and alcohol doesn't have to be the dangerous thing that it becomes for so many folk as they transition into adulthood.