Semenya has 5-ARD, a genetic enzyme deficiency that makes it impossible to convert testosterone into its more potent form, dihydrotestosterone or DHT.

In utero, DHT is what causes the male genitalia to develop properly. As a result of not being able to convert T to DHT, males with 5-ARD are born with external genitals that appear atypical upon visual inspection - though the extent of the atypicality can vary widely, just as with PAIS.

Some males with 5-ARD have micro penises that get mistaken for enlarged clits; some have scrotal skin that looks like (typically fused) labia; some have shallow, blind pouches of skin that go inside the groin and which upon first glance often appear or are assumed to be vaginal openings - and in these latter cases, the urethra often opens up into these skin pouches, giving the appearance that affected persons "pee from their vaginas." This feat of "peeing from the vagina" is often taken as proof that males with 5-ARD really are females, and since childhood Semenya has used it as evidence that Semenya must be female - which just goes to show how little most of the people involved in these convos actually know about the genital and urinary anatomy of those who are genuinely female.

5-ARD also occurs in females, but since DHT has no bearing on female development in utero or any other time in life, in females it's not a DSD. It's only a DSD in males.

Males with 5-ARD have normal sensitivity to testosterone and to DHT and other male sex hormones. There's nothing androgen insensitive about Semenya or other males who have the same male-only DSD.