What is your comfort zone with gaming? What are you unwilling to do as a character, would walk from the game if it was performed upon your characters or would be thoroughly disgusted or terrified if an NPC did something appalling?
I pretty much don't have a problem with anything. I can separate real life and a make-believe world. Some of my characters have performed unspeakable atrocities, things i would shudder if i ever read in the papers that somebody did to somebody else.
Most of my players have a problem with rape, so i never include that in my games. And they have killed children during evil campaigns.
What about you?