For scientific clarification:
The three ways of determining biological sex are chromosomes, gonads (penis, vagina, testes, ovaries, etc) and hormone levels. Some women have levels of testosterone that fall into the acceptable range for men but still consider themselves women, such as the case of South African track athlete Caster Semenya. Others, such as women with
androgen insensitivity syndrome, have male gonads, but those gonads are undescended and their bodies cannot process testosterone. These women look, for all intents and purposes, like "biological" women but are chromosomally male and to some extent gonadally as well. There are even people with extra or fewer sex chromosomes than most, but the vast majority of these people fall into one social designation of gender or the other.
We don't peek down the pants of a PNM, demand their bloodwork before offering a bid for membership or require genetic testing because a woman is a woman if she believes herself to be one and presents herself as one, not if she passes some sort of biological checklist. Sex and gender are different concepts.