Hey my grandpa served in WW2 too! You and I have that in common. And what I mean by that is the deeds or misdeeds of our forebares contribute nothing meaningful to our individual value as people. That is entirely up for you and I to do. It's cool that you're proud of him, but you're also descended from a lot of other people that did both cool and horrifying shit. It doesn't matter that they did it, you didn't. For good or bad, you are judged by your deeds alone.

What did he do, fall out of the guard tower?

Settle down, it's just a meme, no need to go nuclear.