Sometimes on the television show people learn that they had ancestors who were, for instance, always leaving their families. There are patterns that emerge when you are able to look at long threads of generations. And I know myself that patterns exist in my family that explain the ways my relatives functioned. It's only through those discoveries that we are able to come to terms with where we've come from, and forgiveness is the only way to break patterns.
I'm not sure if it's easier to forgive those we know, or those we never met. But it seems difficult in either case.