Hey dr. doc, assuming you are lacking a Y chromosome, you are female. genitals are pretty accurate indicator of sex, but of course it is not always so easy, as you said. if we base it on chromosomes, an even more accurate indicator, it makes the sex determination super easy. as for mosaicism we can look at what the majority of the somatic cells contain, y chromosome or not, and that helps avoid any confusion. thank you for understanding.