I have a black friend, Jamaican, but came to England as a baby, older half sister lives in the US who has never lived here. My friend feels the way her sister and family live and interact is very different, insomuch as she the English sister has a lot of white friends, her American sister is amazed at that. My friend tells me that the trauma of slavery in Black Americans is very much an issue, quite understandably. Friend and I are both into genealogy, of course she hit so many brick walls because as she pointed out even their surnames were not their own but often the plantation owner. There have been several black people featured in WDYTYA who have uncovered such outcomes. I think that is quite possibly something some black people will carry with them.
I have another friend who is ethnically Chinese from Penang and told me her parents could never get past the Japanese atrocities inflicted on Malaysia when it was occupied during the War. I can quite see that anyone who has lived through an occupation and witnessed barbarism is likely to remain traumatised. She and her siblings left their place of birth and settled in various parts of the world, so possibly not as rooted to the past but still aware of it.
I also have a grandma who is part Irish and her people left Ireland in the aftermath of the Potato Famine, I don't think that's affected me other than I'm interested in it, my mother read a lot about it, in fact I have a book sitting on my bookshelf she gave me by Thomas Keneally called "The Great Shame" which I haven't got round to reading. Yes she was very aware of it and on her other side we had French who may have had to flee France during the Franco Prussian War that interests me more.
All the Jewish people I've met have lost someone in the Holocaust. I also had an Armenian neighbour who lost people in the genocide of her people at the beginning of the 20th century. I think it's all a question of how long ago such atrocities occurred and it's understandable that if those losses are among anyone's nearest and dearest the trauma will remain.