@dizzydizzydizzy
I read that. The BBC has never covered itself in glory in being clear in its Sports reporting. Semenya has raised testosterone because he has testes that secrete testosterone, not because he's a special kind of woman with high testosterone. I'm honestly sick of hearing that phrase from them.
That testosterone lead to all the normal advantages of male development - lung capacity, muscle has, bone strength, height, but because the body cannot convert testosterone into dihydrotestosterone (DHT) during early development, external male sex organs do not fully form before birth.
Semenya is male, with a male DSD. Semenya claims to have a vagina but males with 46 XY - ARD develop a pseudovagina, or blind pouch that may resemble a vagina when they are born. They don't have ovaries or a uterus.
The blind vaginal pouch does not develop into a full reproductive vagina; instead, what at first looks a clitoris grows larger, and muscle mass and voice changes occur. At puberty - and as PP have said, at that point, if not before Semenya will have known he's not female.
It's unusual; it's a disorder but it's a disorder of male development, and as such gives male athletic advantage.