If we all agree that a people can experience trauma on a large scale and that trauma can then pass onto the descendants, then the reverse must also be true – a people who have inflicted trauma on a large scale pass that experience onto the descendants.
People who are descended from people from slave-owning and imperialist nations carry with them the scars of slave ownership, genocide, oppression. It shows in the way they act, speak, think. Their worldview is informed by their history as masters of “lesser people”.
Perhaps I should have written “People who were raised by people that…”?
If you think people from Africa are worth less than people in Europe, then what motivation do you have to teach your kids the opposite? You may even keep your racism to yourself, but you can’t change your actions. A little European kid notices that their parents don’t hang out with anyone else but their own countrymen for example. That’s enough for the kid to view everyone else as “the other”.
So it isn’t so much genetics, but what children are exposed to. If a parent small talks and laughs with random countrymen you see around, but then keeps it short with foreigners and doesn’t have the same rapport, children pick up on that.