One complexity is how each of us chooses which groups from the past to identify with. Many people, when they look back only a few generations, find they personally have ancestors from multiple cultures and nations—some of whom may have been in conflict with each other. And then, quite differently, there's the possibility that we learn a lot from understanding and sympathizing with people in a particular culture even though we don't personally descend from anyone who belonged to that culture.

I often think in terms of "history to be conscious of" or "perspectives to understand" rather than "grudges to hold (or let go of)." A "grudge" seems to describe a reaction of an injury done to me personally, and it's tricky to say whether/how I'm personally injured by things some people did to otherpeople before I was born. So I try to focus on understanding injuries, from which I hope an appropriate moral feeling/response will flow naturally—one that's authentic to who I am and honest about what I owe to others.