Yeah, I didn't legally purchase alcohol until I was 19 either. Though I did legally order it when I was 18 at restaurants when other family members were footing the bill.
Honestly, next-to-nothing changed when I turned 18 with regards to my alcohol consumption. I usually drink at home during the sport or whatever. I suppose the only change was that at restaurants, instead of telling Mum what I wanted and getting her to order it, I could order it myself.
And when I travelled around New Zealand vineyards - well, my father's a well-known guy when it comes to wine and he knows people, so there was never the suspicion he was some government inspector and the people at the vineyards were only too happy to pour a little glass of wine for 12 year old me once my father said I should have a try too. My father believed quite strongly in educating my palette young. One of the few things he got absolutely right when it comes to parenting.
