https://www.endocrine.org/news-room/press-release-archives/2006/testosterone_lvls_in_men_decline

Hormones effect behavior. Testosterone levels are higher in men than women, and provides many of the stereotypical "male" characteristics. Muscles, aggressiveness, etc.

Could the "masculinity crisis" be in some way related to this? Could the rise of feminism be in some way related to this?