It is possible to be born male -XY- with DSD and as a result of complex hormone problems it be difficult to identify sex at birth. All XYs are genetically male but faults in expression of some genes mean that they do not develop into easily identifiable male individuals.
It’s all a matter of degrees of variation.
But to the same extent all XX are female.
Interestingly in 46XX male syndrome, development can produce normal male development & puberty ( although there can be micro penis/hyperspadia) but essentially the newborn will be identified as male at birth, but they will be infertile despite all this.
It would be interesting if a male with 46XX syndrome would be eligible to compete as a women based on genetic testing.
So how do we define this very small percentage of athletes who may not fit into the simple boxes of XY-male and XX -female?
Firstly genetic testing, then determining whether a female presenting athlete has gone through a male puberty, because this is where the whole difference lies. I do think that it is unfare on an athlete that despite being “female” they are unable to compete due to a very rare genetic hiccup. But equally it is unfair on competitors if this fault gives them an advantage.
We have no idea, historically, how many DSD athletes have competed and been successful. As someone has already pointed out for a rare condition it seems to be quite a common problem in women’s sport. I think that the governing bodies of all sport are responsible for the safety of the athletes they represent and need a well defined pathway to avoid serious injury and potential litigation going forward.
Many governing bodies only define women’s competitive sport, that is to say you can only compete in women’s event if you are a woman. Men’s sports are often open events so women can compete in these events, however, elite women are unlikely to compete in elite open events for obvious reasons.
It is good to see mixed events in some team sports, swimming being one of them. They used to be considered Mickey Mouse events but are now accepted as legitimate competition.