Many people forget that Germany is not the only country with dark spots in it's history. Just mentioning the Nanking massacre (don't google for it if you can't stand it, there are images you probably don't want to see) as and forcing many mainly korean and chinese woman into prostitution for military including raping them as some of the cruel things Japan did as well in that period.
My grandfather (the german one) was 14 when the war ended, my grandmother even younger. So how do I feel about that? I am not connected to any of the things that happened directly.
It is bad what happened, but I don't feel any shame for being German because of that and that would be stupid. I visited three concentration camps, I was at Verdun (first World War stuff, but still a horrible place), I were at several German and French forts and bunkers, so the only thing that I can say that has an impact on me is that I am able to learn a lot about that time, the why and what because I am able to see the places.
So, sure, "Germany" started to invade Poland and sure, "Germany" build concentration camps (not only for the Jews you know, also gay people, communists, disabled people, gypsies...).
So I am sad about what happened without feeling guilty at all. And I think people should also think about for example the
Third Wave experiment; it is not like that Germany was a country full of evil people back then.
It's a very serious topic and I personally e.g. can't stand Nazi jokes - not because I am German, because I know so much about the cruel things and it is just not funny at all. I mean, it wouldn't be funny either to make 9/11 or Charlie Hebdo jokes, huh?