The game hints at you, very occasionally, for the first 75%, that maybe you ought to perhaps consider being a good person. That's all. The first time I checked my stats and discovered that the game keeps track of how many people you've killed by driving over them with a stagecoach, with a cart, with a wagon, OR with a plain old horse, I knew what I had to do.

It also differentiates between "horse assault", "horse slaughter", "livestock assault", "livestock slaughter", and "cruelty to animals". Kicking a chicken does not qualify as any of these things; I checked.