Who, exactly, is your audience? Who do you write for?
It’s a question worth considering because the nature of your audience should influence the way you write. The stand up comedian probably won’t perform the same routine in front of a group of college students as she would for a religious convention. The audience must determine the material in some way.
The same concept applies to our writing. Every genre has its conventions, assumed rules of design and conduct that the reader expects when he picks up the work. It does not matter what the genre is, romance, sci-fi, detective, mystery, western, every reader has certain expectations when he picks up that work. Mess with those conventions at the risk of forever losing the reader. (Or being rejected by a risk-wary publisher). For a strict set of genre guidelines, check out the Harelquin Romance site sometime at http://www.harlequin.com.
Can you have the protagonist of your western be a gay pacifist? Certainly. But be prepared for some backlash.
That being said, not all genre conventions are iron-clad. Fifty years ago there were few, if any, female leads in detective fiction. Now they are common. The conventions are flexible and change with the times. Whole genres such as steampunk and cyberpunk didn’t even exist a generation or two ago. The rules can and should be bent. The boundaries need to be pushed.
The danger in writing to the conventions in any genre is that the work starts becoming formulaic. How many times have you read three or four books by an author and found each had basically the same plot? In my opinion, that is not what we, as writers, are shooting for.
The solution to the entire problem is relatively simple. The audience that must always be in the forefront as you write, the one you should be striving hardest to please, is yourself. Know the genre in which you’re writing. Read every example you can find until you know the genre inside and out. Then write a story in that genre you would like to read. Write a story you find interesting, thrilling and compelling.
Do that and the rest will take care of itself.