I don't want to go deep-diving to find the study again, but basically:
* All men view all other men as Out-Group, no different than how niggers look at whites or jews look at goyim
* All women view all other women as In-Group; sisterhood mafia, women are jews
* All men view all women as In-Group
* All women view all men as Out-Group
To put it another way: everyone loves women by default, everyone hates men by default.
Expect A LOT of light bulbs to click on once you look at the world, history, personal experience, etc. with this knowledge.