My impression, and the impression of many other women I have discussed this with over the years, is that women are generally extremely adept at accurately telling the sex of other human adults and adolescents. I believe we're much better at it than men are.
The ability to be able to determine the sex of other human adults and adolescents, and to do so very quickly, is one of the self-protective skills girls and women rely on to help us stay safe. As the physically slower, weaker, smaller, less explosive and less powerful sex, we have far less of a chance of successfully defending ourselves or getting away if a man or teenage boy attacks us.
But it's more than that. Because most males are heterosexual - and many men and adolescent boys are sexually aggressive and always on the prowl; some are prone to intrusive, abusive and even violent behaviors ranging from leering, catcalling and voyeurism to "copping a feel" and flashing to stalking, menacing and rape; and many boys and men do not see female humans as worthy of the same basic respect and courtesy they think males deserve as a matter of course - when girls and women go about our daily lives and move through the world, we get targeted and preyed on by men and boys in ways, and with a frequency, that males do not experience.
Beyond the fact that females face a much higher risk of being preyed upon and abused sexually by men and boys than males face, once females reach puberty and for about the next 40 years, we also can become pregnant. This makes us vulnerable in cases of sexual assault in a profound, and profoundly terrifying way, that males never experience - and which many males can't imagine and never take into consideration. Whilst it's true that some men and boys rape others of their own sex - particularly in certain settings like in male prisons - for men and boys who are raped, their rape trauma is never compounded by the dread and horror that comes from knowing that rape might have left them pregnant. After a sexual assault, males never have to follow-up going through the forensic exams used to compile a "rape kit" by taking pregnancy tests in the days or weeks that follow. They never have to deal with the emotions and ethical dilemmas that female rape victims must cope with a post-assault pregnancy test is positive.
For these and other reasons, I think women's ability to be able to correctly assess and guess the sex of other human adults and adolescents, and to be able to do so very quickly and without much conscious thought, should be seen as a "sixth sense" and regarded in a positive light, as a strength. But in the controversies over athletes like Semenya, Niyonsaba, Wambui - and now Mboma and Masilingi too - this finely-tuned and probably at lest partly instinctual sense that most women possess has been used against us. Women who immediately and intuitively can tell that athletes like Semenya, Niyonsaba and Wambui are males and who have had the audacity to say so aloud (like Lyndsey Sharpe) have been lambasted as sexist, racist bigots full of misogynoir. Instead, we're all expected to stand by and politely and silently smile and nod as though we believe the party line and total lie that said athletes are merely "women with naturally high testosterone" - or they are "intersex" women with mysterious medical conditions affecting female development, anatomy and physiology that are so unfathomable that even in the age of advanced medical knowledge and testing, no one earth has figured these conditions out yet, and never will.
Worse, for knowing the difference between males with DSDs like Semenya and Niyonasaba and females who happen to butch, masc or "gender nonconforming" - and women who truly do have "hyperandrogenism" chronically and high testosterone temporarily due to female-only conditions such as PCOS and pregnancy - we are told we are have a colonialist white supremacist mindset that causes us to judge other women through the lens of racist white European beauty standards.
Meanwhile, Semenya, Niyonsaba et al get lionized in the global media as civil rights champions, and celebrated as national heroes in their home countries - countries where the lives of actual women and girls are made unduly difficult due to widespread sexist discrimination and abuse, lack of contraception and female health care, and high rates of such problems as menstrual shaming, "period poverty," forced marriage of girls, teenage pregnancy and motherhood, pregnancy-related mortality and disability, and "corrective rape" and murder of girls and women thought to be lesbians or viewed as "too sporty." Semenya especially is constantly held up as a sterling example who epitomizes and represents the kind of "strong black African women" who've been able to shine and prosper in the post-colonial era, particularly since the end of apartheid. When the reality is, the massive amounts of money, resources, time and attention devoted to supporting, promoting and celebrating XY DSD athletes like Semenya, Niyonsaba, Wambui, Mboma and Masilingi has done real damage to all the female runners in those athletes' home countries who never got a chance to have careers in athletics because they weren't born with testes. And when the reality is, female people who appear butch or masculine in countries like South Africa, Burundi and Namibia are scorned and bullied by both sexes - and they are raped, assaulted and murdered by men and boys in high numbers.