My daughter is only two, but she has asked if she could try my wine/dh's beer. I am not 100 percent certain she would hate the taste, so I don't give it to her- she's the sort of toddler who literally likes every food that we put in front of her, even things that many adults think taste odd (the only exception being mashed potatoes- for some reason she does not care for mashed potatoes. strange...) I usually tell her she can try it once she's six or seven. I figure by then her taste buds will be a bit pickier and she will be more likely to not like the taste. If she remains a gourmand, however, I will probably let her try small sips once she is twelve or thirteen. Drinking real, adult sized servings of alcohol? I don't imagine I will actually approve of that in our home until she's eighteen, except for very special occasions. This is not to say that she would get into massive trouble if she was caught drinking with her friends or something- I hope we will have mutual respect and trust at that age and she will know to call me if things ever get out of control or she finds herself in a scary situation or without a sober ride home.
I drank a good bit and was quite a party girl in high school and college... I don't want to encourage that sort of behavior in her. But if she is by all accounts a responsible and stable teenager, I might change my mind and let her have wine at home on a more regular basis.