Oldman, must admit that I'm with Yankee. Doesn't bother me to kill the humanoids... but I won't attack first. But hate having to kill animals...and yes, I know they aren't real....but then, neither are the people. Been this way my entire life. I also don't watch movies or tv shows or read books where animals are killed.
I have a rogue in WoW, and I love her, and made a toon on a PVP server since rogues are usually a gank machine. But I could never make myself attack another player.tried and tried and just could not do it...stood there invisible going "push the button, push the button"..so rolled one on the non-PVP server and happily smack down the NPC's
Now, people in the battlegrounds are fair game, and fun! But that's a whole different topic