The Nazis - and Hitler specifically - had a public image to maintain. Which they did. It was about national pride and getting jobs for everyone who wanted to work and getting rid of the inflation that had been a serious problem after WW1. Hitler was known for his exceptional charisma. So the stuff about concentration camps and war crimes that we know about know was still in the closet back then and wasn't part of the image. People don't need to jump on it.

My guess is that your parents aren't going to be prepared for a complete answer any more than people here seem to have been. So you will have to make up something else or tell them that maybe some movie or another triggered your interest.