Expectation and Expectancy

It's something I've realized many times before, but now it seems to be cropping up more and more. It's something I'm sure many other people have to deal with, but it's starting to get to me.
It's called expectation.
See, people have expected so much of me because of how generally conservative I am. But I've been drinking a little alcohol, smoking cigarettes, and whatever else, and people seem to think it's below me. I waited until I was 21 to start drinking (if not a couple weeks before), and I've been smoking since 19. So I've kept it pretty legal, but people seem to think it's morally beyond me. Understand that it's not. Why am I not "allowed" these pleasures when others get away scott free.
I guess the best comparison is to say that I have always been a straight A student, and my friend gets mostly C's. So when I get a C, I catch flack, but when he/she gets a C, it's still perfectly fine. Why can't we both be held to the same standards, regardless of past history?
Well, anyway...
I'm gonna do what I wanna do. If I have a friend in you, I'm sure you'll be okay with that. Unless I kill someone. You don't have to be okay with that.
Speaking of which... why in the HELL does everyone think I'm going to become (if I'm not already) a serial killer??? Bothers me a little. I have honestly been told on multiple occasions by both friends and coworkers that they wouldn't put it past me to be or become a serial killer. I suppose just remind me to delete this blog if I do start killing people.=|