The Spectator newsletter reports:

Hitler may have had only one testicle. So claims forensic DNA specialist Professor Turi King in a new Channel 4 documentary. According to polygenic analysis, the dictator had a deletion in his DNA which affected the protein needed for the development of sexual organs. Turns out the British were right, Hitler has got only one ball: but how on earth did they know?

They knew because the other is in the Albert Hall.

But whether Himmler was very similar and Goebbels had no balls at all is open to debate.