"Claims that trans women are not women often rely on essentialist (and therefore incorrect) assumptions about biology. For instance, people might argue that trans women are not “genetically female,” despite the fact that we cannot readily ascertain anybody’s sex chromosomes. Indeed, most people have never even had their sex chromosomes examined, and those that do are sometimes surprised by the results. Other common appeals to biology center on reproduction — e.g., stating that trans women have not experienced menstruation, or cannot become pregnant. This ignores the fact that some cisgender women never menstruate and/or are unable to become pregnant. Claims about genitals are similarly problematic: Women’s genitals vary greatly, and as with chromosomes and reproductive capabilities, we cannot readily see other people’s genitals in everyday encounters. If you and I were to meet, should I refuse to recognize or refer to you as a woman unless you show me your genitals? And frankly, what could possibly be more sexist than reducing a woman to what’s between her legs? Isn’t that precisely what sexist men have been doing to women for centuries on end?"
January 1, 1970
https://en.wikiquote.org/wiki/Trans_woman