I was playing Doom when I was 4: I'm a pacifist.
I think the whole violent video games = violence thing is nonsense. I'm sure a correlation exists, but that's because violent people will be attracted to outlets for their violence, particularly violent movies, music and games. Not everybody who reads a book (or watches a documentary) about genocide wants to commit genocide: it's an illogical argument absent of causal evidence.
With that said, I understand the concern - and recommend Torchlight and Torchlight 2. It's the same gameplay as Diablo 3, but without the splatter-gore effects. It's like Fisher Price presents Diablo 3