Studies show women have an incredibly strong in-group bias - 4.5x higher than men. Meanwhile men have no statistically significant in-group bias.
Think about that. 4.5x. 450%.
It's really difficult to imagine the incredible ways such a strong in-group bias must color their thinking on virtually everything. That's why I'm never surprised that the majority of women automatically side with women, even when it means ignoring facts and evidence.