As an American businessman attending meetings in Germany, I have had to bite my tongue frequently. For example, over dinner in Berlin with some wonderful German beers, I had to suppress the strong urge to blurt out, "This is a beautiful city, especially considering the pounding we gave it seventy years ago." I wonder if my counterparts also ever stop and realize that two generations ago, our relatives would have been doing their best to kill each other. So far, at any rate, I've managed to keep Basil Fawlty's directive, "Whatever you do, don't mention the war!"
On the plane home the other day, these thoughts led me to what might be a commonplace observation: I could never imagine the Germans I've met throwing their support behind anything as vile as the Nazis. Now, there are some traits that are stereotypically German which I see in abundance: they are serious, hard-working, comfortable with hierarchy. You could see how they would make good soldiers: they seem like they would take to discipline very easily. But for the evil of Nazism to take hold, you would expect there to be some hint of that darkness in the character of the people, and I at least haven't seen it.
This is important because many materialists will tell you that free will doesn't exist in any meaningful sense. History and individual behavior are essentially pre-ordained. But if this is true, our personal and group behaviors must come from our DNA, and if so, it must be relatively immutable, certainly in the span of a few generations. People capable of aggression and cruelty on an industrial scale, especially people with a relatively homogeneous population, should show at least that potential relatively constantly.
I'm sure some clever materialist has come up with an explanation for this: the most plausible is that these cultures mask their traits as they recover from a defeat. But I think it much more likely that choice makes all the difference. The free will of parents to raise their children to hate violence changes the way they will feel as adults about war. Teaching ethnic and social tolerance will reduce fear of the other.
The good news is that our DNA does not determine our behavior, and whether we embrace good or evil in our lives. The bad news is that our DNA does not make us immune to the kind of evil that overtook Germany in the middle of the 20th century. If society makes bad choices, it could happen anywhere, including here.