You know, "intersex" isn't a category. It's a catch-all term for disorders (or "differences" to be politically corrext) in sexual development. There are about 40 or so distinct conditions under this umbrella and in the vast majority of these cases there is no doubt at all as to the person's sex. These are males or females with a recognisable abnormality of some sort. Even hypospadias is included in this category but I don't think anyone would claim that a child with hypospadias isn't a boy.
In a fairly small minority of cases the sex of the person is indeed ambiguous, at least on external viewing. However genetic and other testing can correctly classify these people as well. If Caster Semenya had been born in a different society with better access to healthcare as a baby it's quite possible she would have been discovered to be male at that stage, and brought up as a boy. Since that didn't happen we don't know how she would have developed. All we know is that she was brought up as a girl and has never sought to claim a masculine identity.
However, "intersex" individuals cover a wide variety of different conditions and they can't be put in a single box and told, here, this is where you compete. Once again the males would trounce the females. And as I said, even people with DSDs are either male or female.
While it's true that in >99% of cases XX chromosomes make a girl and XY a boy, there are a small number of exceptions to this. In fact, the presence of a Y makes a boy and the absence of a Y makes a girl. To go further than that, it isn't the Y chromosome as such that makes a boy, but the presence of an SRY gene (which is usually located on that chromosome). However some XY individuals do not have a functioning SRY gene and these develop as girls (Swyer's syndrome). Conversely it occasionally happens that an X chromosome has an SRY gene translocated on to it and someone with this genotype will develop as a male even though the genotype is XX.
So, functional SRY gene = male, no functional SRY gene = female? Not quite.
In order for the SRY gene to produce a male foetus, functional androgen receptors are required. Thus someone with an XY genotype, and an SRY gene, but who has no functioning androgen receptors, will also be female. This condition is known as CAIS - complete androgen insensitivity syndrome.
So, absence of SRY gene = female. Presence of functional SRY gene but absence of functional androgen receptors = female. Presence of functional SRY gene and functional androgen receptors = male.
It is Caster Semenya's misfortune that she is in the third of these categories. She is genetically XY, but this was concealed for many years (until yesterday as it happens). She was always presented as a hyperandrogenised, virilised female, and on that basis I and many other people vociferously supported her right to compete as a woman. (The condition she was believed to have is late-onset adrenal hyperlplasia, where a woman's adrenal glands make abnormally large amounts of testosterone.)
We were misled. Caster Semenya is XY, but was born with her testes located internally and the external appearance (as a baby) of being a girl. The cause of this appears to be a poor but not nonexistent response to androgens, known as PAIS - partial androgen insensitivity syndrome. (This part is informed speculation at this stage.) She was brought up as a girl in perfectly good faith, until at puberty she began to look more and more masculine. She competed in women's athletics, with the partial and misleading information that was made public leading everyone to believe she was XX with a virilisation syndrome. However, she had been tested and the SA authorities knew perfectly well this wasn't true. The athletics federations must have known too.
If this had been the 1970s she'd have been disqualified as soon as her genotype was discovered, but it wasn't. This was the time when the athletics authorities were caving in to pressure from the trans rights activists to open women's sports to male-bodied people. And it appears that they were content to let Semenya's case slide past, possibly because of these ongoing developments.
Semenya has become more and more obviously masculine as she has matured. She has a Y chromosome and that Y chromosome has an SRY gene on it, and she clearly does not have CAIS (
this is what someone with CAIS looks like). She may well have PAIS, but she has functional androgen receptors as can be clearly seen from her evidently masculine phenotype, and this is proved by the fact that medically reducing her testosterone concentration significantly reduces her performance.
The new rules to allow males to compete in women's events required male-bodied athletes to lower their testosterone to below 10 nmol/l. The gross unfairness of this to actual women is something I will leave aside for now. In fact this did not impact on Semenya, because while normal male testosterone will spike to 40 to 50 nmol/l, she didn't go above 10 nmol/l naturally. (Normal female concentration is more like 0.5 nmol/l.) So that was fine, Semenya didn't have to take the testosterone-lowering drugs.
Then it was proposed to lower the ceiling for women's events to 5 nmol/l, to go some way to addressing the manifest unfairness of the 10 nmol/l rule. This
did impact on Semenya, who has natural testosterone concentrations over 5 nmol/l. She knows that if she reduces this, her performance will be impacted. So she appealled to the CAS on the grounds that as she was actually a woman, this rule should not apply to her.
This is where it gets murky. On the assumption that she was a hypervirilised XX, many people (including me) supported her. However, she's not a hypervirilised XX. She's XY. She is, technically, biologically male, and the CAS knows that. She's not an advantaged female, she's a disadvantaged male. They ruled that as a biological male, she is subject to the same restrictions as other biological males who are permitted to compete in women's events. She has to lower her testosterone.
And this seems like a just ruling to me. The CAS was quite explicit that if the situation had been as we were all led to believe, that she was XX with adrenal hyperplasia, she would have won the case. But she's not, and so she lost.
And she has lost badly, because her XY genotype is now public knowledge, although it was something she really didn't want known. The people who said "look at that, that's a man" are feeling vindicated right now. Goodness knows what this is doing to her mental health.
But it seems the SA athletics authorities were too keen to keep the star runner on their team, without her having to lower her testosterone, that they forced the issue regardless. Despite knowing that she was XY and biologically male, they tried to browbeat the CAS with allegations of racism and discrimination to bully them into treating Semenya as a female. The CAS declined to be bullied, and now the whole story (or most of it) is public knowledge.
It's a real shame for Caster Semenya, but it was the right decision.