Well when it comes to medicine it's a little different. I think opening up your torso is frowned upon in polite society, for example, but when used for a precise medical purpose it can be worth the trouble. More specific to pharmacological arguments, for example I regard my medication not so much as "fucking it up" as
correcting a neurochemical mistake. It's been carefully prescribed and I take it precisely as I am told, and it has the given and expected effects because a doctor monitored me when I first took it to watch for side effects, etc.
Ah, be careful. My mum's like that, and her very stringent anti-alcohol stance made my relationship with the stuff a bit... complicated. Less would have been more in this case.
Well my mother said very little at all. Perhaps if I got caught reeking of alcohol or something she would have changed her tune, but she was pretty solidly in the "don't be stupid, have fun" category. And that led to both of her children becoming teetotalers. Where does that fit in your schema?
The answer is probably that alcohol usage doesn't directly correlate to what your parents tell you about alcohol, but to other factors like availability, level of drinking in the home (which was nonexistent at my house, although my mother has no rule against it; it's just an unnecessary expense), how your parents treat you in general, socio-economic category, the type of friends you have, etc.