this is an interesting topic. I tend to think that what makes "bad" people different is not that they have some kind of evil in them that we don't, I think rather they lack goodness which would keep the evil in its place. I think basically if you could erase the good out of anyone , what would be left would be a calculating, evil, psychopath. we all have it in us but our empathy and desire to be loved keeps us from acting out the evil side of us. I think this is why people have a fascination for serial killers, the beast within us admire the freedom that they represent, the absence of barriers preventing us from acting out our raw, selfish will. I also think this is why our movies and especially video games are so violent. we are all psychopath with a conscience but when we find ourselves in a video game when killing is permitted, we let the beast out but in real life we have compassion, empathy, love, sense of belonging to a group and so on, which are emotions that are more important and more consistent with survival and happiness. but since sociability is a very human trait we can imagine that there must certainly be a genetic factor to this which means that someone could be born without this gene of sociable disposition and be more prone to chaotic or evil behavior.