How do you know the sex of a chromosome? Pull down its genes! If only it were that easy...

Today, Team SA arrived back in South Africa after the World Championships in Berlin. The welcome home ceremony was really about one person - Caster Semenya, and the scenes in Johannesburg were just extra-ordinary. We have never seen such a huge reception for an athletics team (or even Olympic team). What a pity the "congratulations" was clouded in the controversy and political rhetoric that has now come to dominate the story.

I have some science to put out there, but to introduce that scientific discussion, I first want to put out some quotes from Leonard Chuene, who is the president of Athletics South Africa:

“Let me warn professors and scientists that the only scientists I believe in are the parents of this child,” Chuene said. “One scientist from a stupid university somewhere is going to erase the entire life of this girl.” The IAAF is still awaiting the results of the tests but Chuene refused to clarify what the process was or what would happen depending on the results.

“Why should we worry about other people’s tests?” Chuene said. He also sent out a warning to the IAAF not to punish Semenya. “We are here and one thing they mustn’t do is suspend her.”

Honestly, I couldn't make this up if I tried, those were his exact words. So, I think it safe to say that everything from this point onwards is not of concern to anyone in Athletics South Africa, since it involves my attempt at explaining some of the science around this matter of sex testing and why it's so complex.

Intersex conditions and biological basics

Last week, when all this broke, I said that at some point, I'd pull together the basics of the biology of these conditions, and put it out there for you to read. I must stress that these are basics, and they don't nearly do justice to the complexity of disorders of sexual development, or DSDs.

DSDs are the disorders that are often responsible for producing what is known as the intersex condition, a condition where a person develops ambiguous genitalia, and often, their genetic sex (determined by the chromosome) differs from their phenotypic sex (their exernal appearance and physiological functions, to be broad). In other words, if you have thought that XX = female and XY = male, you are about to have your perception challenged!