Everything we call "evil" that people do is an excess of people's biological impulses, which at some point in our biological past, may have aided our survival.
The default state of man is not good, it is savage, and only through self-discipline do people overcome their savage nature.
So if a person wishes to be "good", there has to be some deeper motive than our mere biological impulses, or else when a person refrains from actions such as theft or murder, they're not doing so with any intrinsically "good" motive, they're simply doing what's expedient then and there (refusing to harm others out of fear of the law, not out of any genuine overarching concern for morality or humanity).
But if in another place and time it was expedient to do the opposite, there's no overarching reason why they should not.