I can't remember when I had my first alcoholic drink, but I remember drinking martini and lemonade at age 17 and feeling very sophisticated (I know...) and even more bizarre, enjoying Liebfraumilch at family dinners around the same time. I also liked Chartreuse and Advocaat.
A few years after that I started to enjoy the taste of Guinness. That might actually have been my first drink, because my mum says that when she was breastfeeding me, the health visitor advised her to drink a half pint of it regularly.