Maybe for power? The Nazis might have known that if you wanted to break a family apart, you could take the kids away from the parents. Since the parents dont want their kid harmed, or worse, they probably would do almost anything to save them. This might result in them fighting for the Nazis or supporting them, in order to save their young. With the parents depressed and searching for their young, the Nazis might have a smooth and easy takeover.
God bless
