Evil isn't just deliberate genocide (which still exists anyway, I have met people who have literally run across entire countries to flee the war in the Sudan).
I think of it more as thoughtlessness and selfishness.
For example, there are plenty of politicians who are willing to do morally objectionable things to a vast number of people to gain an insignificant number of votes even when arguments in favour of those things have been falsified.
I also see my characters' decency as a holistic thing.
Like, the Ashcroft children were essentially an experiment, so they get emotional trauma points for that (although not many), but they were also had a decent upbringing so they know when they're doing something morally objectionable.
Whereas, Liesl Dolohov's father has been on the run almost her whole life and her family moves around a lot. She has a very shaky idea of what's morally sound in the first place, because until she came to Hogwarts, she had no appropriate role models.
So even though Liesl has a lot of potential to become "evil" I don't think of her as an evil character, whereas when any of my Ashcroft characters do something wrong I'm far more harsh on them.
When I'm writing the dark sides of my charries, I don't really empathise with that part of them, anyway, because I write characters with parts that I don't like. In fact, I love being obvious about stupid things about my characters. Like how Monroe is a hypocritical social justice crusader.