I don’t know if the Hitler thing is true, folk legend, or carefully planted propaganda by the allies during WWII.
I don’t know how to find out, either.
His nephew, one Patrick Stuart-Huston (formerly Patrick Hitler) ate at a restaurant, and left behind his napkin. A person interested in such things took up the napkin and had the DNA analyzed. It had Jewish and Berber markers in the DNA.
Hitler’s father was the son of Maria Schickelgruber, who had worked as a domestic for the family of Leopold Frankenburger, a Jew. It was suggested that Hitler was the natural son of Leopold Frankenburger.
Hitler’s commander in WWI was a Jew. He survived WWII and asserted that Hitler had only one testicle.
Hitler had SS#1. His driver/bodyguard and friend Emil Maurice had SS#2. Himmler had #5.
Himmler’s investigations found that Maurice was Jewish. Hitler refused to drum him out of the SS, perhaps because Hitler wanted at least one friend in the world, perhaps because he knew that Himmler would use it as a precedent.