Ok, so you know how sometimes people do things that are really, really mean or bad? Maybe they steal or hurt someone else on purpose. That's what we call being "evil" or having an "evil" nature.
Well, some really smart people have tried to figure out why some people are like that. They came up with something called the "theory of evil human nature."
Basically, this theory says that some people are just born with a bad side to their personality. It's like a little voice inside that tells them to do bad things, even if they know it's wrong.
But, here's the important thing to remember: just because someone has a "bad" part of their personality, that doesn't mean they have to act on it. Everyone has the power to choose to do good things and be a kind person.
So, even if some people might have a tendency to act "evil," it's up to them to decide whether they want to be a good or a bad person. And, if they choose to be good, that's a really great thing!