Yeah, I saw that given as a reason on a TV show not too long ago. Not sure it is correct though because there is a photo of him attending a rally in 1919, well after WWI ended, with a full mustache.
Two things are certain though: that man ruined the toothbrush mustache for all time (have you ever seen one on any person after WWII?) and nobody but nobody names their child Adolph.
He has some relatives apparently living in the US, children of a cousin or something similar. But they use a different last name- not a big surprise there.
Brian
Speaking of Hitler's mustache. Did you know that the reason he sported such a funky mustache was so he didn't have any leaks in his gas mask?