The Sins of the Father

I've been doing a lot of thinking about this recently and I've often wondered: how far can one one reasonably hold someone else responsible for what his ancestors or countrymen did centuries before he was ever born? For some examples, I've been reading about reparations to black Americans for slavery and while I have as yet not discovered any individuals forced to pay reparations it seems only logical in the scheme of things that some have. Also, the Germans and the French still take a lot of grief about Nazism and surrendering respectively. Yet, very few Germans and French alive today were even a part of World War II. And of course I always run across people who declare that crimes perpetrated by people claiming to be of the Christian faith should be shouldered and apologized for by actual Christians living today (never mind the fact that these crimes are hundreds of years old and no one alive today was a part of them).
Now, my heart breaks every time I see the state the world is in and I do everything I can to help everyone I can. I also accept responsibility for my own actions and I do everything I can to improve the poor state this world is in. So I guess my question is: can an individual truly and logically be held responsible for the actions of other people dead and buried?