I have about as much faith in NASA as I do in the rest of our government, but I'm leaning toward real based on what I've read. Although considering Nazi scientists were likely the brainpower behind it, lauding it as an American achievement is probably overblown.
So the genetic make-up of the people involved means it is a German achievement? Why did it happen in the US then? One, because we defeated Germany in an all out war. Two, our stable, non-corrupt government, non-slave taking, non-genocidal society, free-market based economy, individual rights respecting culture, is the best possible place to achieve such things.