Turns out part of Adolf Hitler's twisted psyche might be explained by a particularly embarrassing medical condition: He only had one testicle.

A German army medic revealed der Führer's long-suspected anatomical issue to a priest (who wrote it down) in 1960, but that priest's note only recently emerged. The medic saved Hitler's life during a battle in the first world war, and confirmed that Hitler lost a single gonad from his injuries.

For those keeping track at home, "monorchism" is the technical term for the condition of having a lone nut.