What would’ve happened if Adolf Hitler had been born a girl?
A counterfactual history is a sort of story telling device, sometimes used by historians to amuse themselves (and us), but also used to analyse how important a particular historical event was in shaping the course of history, by imagining the course of history had the event not happened, or happened differently.
The classic case is: What if Hitler had been a girl? So you might argue that the Nazi party would not have taken over Germany and World War II would never have happened had that sperm borne an X chromosome instead of a Y, in which case that sperm would’ve been extremely important. Or alternatively you could perhaps make the case that Hitler’s sex was unimportant, or that someone else equally determined would’ve propelled themselves forward in the desperate Germany of the 1930s to take revenge for the defeat of World War I, and everything would’ve worked out pretty much the same, in which case the Hitlers’ gametes wouldn’t be important at all.
So I’m being flippant–usually the analysis is of things like what if Hitler hadn’t invaded Russia, or had been assassinated by Tom Cruise in 1944, and so on. It may be because my interests lie elsewhere, but asking what might’ve happened had such and such an event happened/not happened seems to me to be a bit of a pointless exercise. I contest however that counterfactual analysis is more interesting when applied to ideas…