I suppose this question only has real meaning for anyone who has a kid. But I suppose a lot of people would be unable to kill their own child even if their kid did awful stuff like kill other people. I think most people would only be able to bring themselves to send their kid to jail. Obviously this is in reference to killing Shaun in the game.
Would you kill your own kid if he was evil?
My girlfriend had the funniest response. "Depends if he's rich. For example if he was a Mexican drug lord and loaded I'll tolerate him killing people".