Simplified answer that is not flippant: Testosterone. Hormones have an enormous impact on how we think and behave. Testosterone numbers is a ‘ratio’ and not an

Simplified answer that is not flippant: Testosterone. Hormones have an enormous impact on how we think and behave. Testosterone numbers is a ‘ratio’ and not an absolute number. So this keeps changing all the time. For women, this skews wildly during PMS when they have a surfeit of testosterone as a ratio. Which gives rise to all the lame jokes about ‘that time of the month’. But men deal with that elevated testosterone as a ratio throughout until middle age. Men go through ‘andropause’ too, but don’t get enough support. Women get used to mood swings and wild variations in their hormone level right after menarche. This is also why while gender transitioning, MtF is more brutal on mental health than FtM.