Comment by sltkr

This question is usually asked in bad faith, but I'll bite.

Gender ideologues or genderists believe that whether someone is a man or a woman is determined primarily by that person's gender self-identification ("A woman is anyone who identifies as a woman").

This in contrast with the classic belief, held by radical feminists, J. K. Rowling, and many others, that whether someone is a man or a woman is determined primarily by the physical attributes of their bodies related to biological sex (genetics, hormones, gonads, etc.)