Semenya was the 18-year-old who sensationally won the 800m at the 2009 world championships. Because of suspicions around her appearance, she was required to undergo gender testing - a demeaning process handled so poorly by the IAAF that the whole process was replaced by setting an upper limit for testosterone in the female body. The implication was that, above that limit, a sheila is technically a bloke for the purposes of competition.
Media reports alleged Semenya had unformed testicles inside her abdomen and about three times as much testosterone as a "normal" woman. Semenya was required to take hormones to balance out her testosterone advantage.
But the new system failed. Last year, Indian sprinter Dutee Chand won a case at the Court of Arbitration for Sport after arguing she had naturally high testosterone levels and it was discriminatory to deny her use of her genetic gifts.
It's hard not to agree - and the CAS did. After all, 2m basketballers are not punished for being tall. Nor was Australian swimmer Ian Thorpe pilloried for having size 17 feet or Kenyan athletes for being born at altitude.
The problem for officialdom is inconclusive science. Some people - estimated to be one in 15,000 - have female form but male chromosomal characteristics to the extent they would fail the old sex test. Some women have totally female characteristics but carry male genes. Some have small testicles hidden inside the abdomen, but not all with high testosterone levels are able to convert it to aid performance. Proof is, so far, impossible.
When CAS found in Chand's favour, the hormonal handcuffs were off. The IAAF declared a two-year suspension of the rules while they attempted to sort things out. Semenya does not have to take her balancing hormones and is free to express herself. Her most difficult opponent, a Russian, is facing a life ban for drug abuse.
Reports from South Africa have suggested Semenya will win the Olympic 800m by about 20m.
Last month she won the South African 400m title in 50.78s, the fastest time in the world this year. After a 50-minute rest, she won the 800m in 1m 58.45s, also the best time this year - until she bettered it this month. Three hours later, she easily won the 1500m.
Observers said she seemed to be coasting. Other reports suggest her silver medals at the 2011 world championships and 2012 London Olympics were the result of a young woman not wanting to stir controversy by winning gold - her London medal came when she gave the winner an impossible start before storming home.
If you are in any doubt about the storm waiting to break, consider these two assertions from athletes competing against her in 2009.
Elisa Cusma of Italy said: "She's not a woman; she's a man."
Canadian Diane Cummins, who ran against Semenya in her 2010 comeback, said: "We have levels we are not allowed to test over, so even if she's a female, she's on the very fringe of the normal female athlete biological composition from what I understand in terms of hormone testing. From that perspective, I think most of us just feel like we are running against a man - because what we know to be female is a certain testosterone level.
"If that isn't the case, they need to change everything."
But surely Semenya and people like her - if they are naturally endowed - must be given licence to use those endowments.