As this is a minefield, I will state my expertise from the get-go: at one point in my life, I published scientific papers quantifying the level of hormones. Plant hormones, rather than human ones, sure, but I feel qualified to comment on the science behind this case, and my position is that the media is failing to convey something hugely important. Once I make this argument, I also hope to convince you, dear reader, that science fiction needs to pay attention to these issues.

The International Olympic Committee uses one absolute criterion for splitting the human race into two genders: level of testosterone. Testosterone levels vary. The women with the highest five percent of the bell curve distribution are indistinguishable from men at the lowest end of their bell curve.

Two conclusions: (1) Using testosterone alone is a stupid way to distinguish male from female; and (2) There’s something more to the biology of what determines gender. Gender is real; to state the obvious, males cannot have or nurse babies (okay, pre-operative trans males will not choose to have or nurse babies), and many females can. The response to androgens does play a major role in gender-specific development that makes this biology possible.

Nonetheless, testosterone is only one component of this response. In the bloodstream, testosterone is activated to its more active form, dihydrotestosterone. The enzyme responsible for this conversion is present, on average, at triple the level in XY fetuses as compared with XX fetuses. Also in the blood, there is a protein that binds to testosterone and keeps it away from its receptor, making it biologically inert. When researchers compared high-testosterone females with low-testosterone males, they found that this protein was present at a 50% higher average level in the females. Both of these factors mean high-testosterone women experience a lower concentration of testosterone activity than low-testosterone men.

The testosterone response system is also highly regulated. Many small molecule additions modify the receptor that binds to testosterone and alter its ability to transduce the signal. The gene for the receptor is also modified epigenetically, affecting the level of testosterone receptor that is made. The testosterone/receptor complex binds DNA and functions to turn on androgen-regulated genes, but it doesn’t function alone. Many other cofactors affect the activity of these genes. All these components are present in both males and females, but the differential regulation dramatically affects the level of testosterone signaling, further differentiating male from female.

Most or all of these gender-specific differences contribute to rendering Caster Semenya unambiguously female, despite her high testosterone level. As such, relying on this one criterion to deem her “not female enough” is stupid. From the point of view of hormone biology, gender is a multidimensional spectrum. Someone whose genitals are those of one gender may have brain activity characteristic of the other because all of these levels of regulation play out differently in different tissues.

So, if enforcing a binary paradigm for gender is biologically unjustified, why do it in sports? The answer, according to the Court of Arbitration for Sport, is that discriminating against high-testosterone women is less harmful than effectively banning nearly all women from the Olympics by not allowing men’s sports and women’s sports. The woman who can compete effectively in a “men’s” sport against men at that level is rare. Do we really want to tell every little girl in the world that the only good athletes are men?

Let’s go a few decades into the future. At that point, it will be possible to determine a more relevant criterion for gender. Take every biological pathway that contributes to a physique better suited to a particular sport. Look for those in which the bell curve around the average response differs markedly for men and women. Develop a combined metric. On purely scientific criteria, one could then say that an athlete is “female enough” in some sports but not others.

But why do we care about any of this? Isn’t the overemphasis on sports pretty stupid? Well, some people find it entertaining. It is thus lucrative for the top athletes. Going all the way back to the ancient Greeks, it was looked at as a less harmful way of competing between nations than going to war. Still today, for small countries, having an Olympic medalist is a great source of national pride—something that brings a nation together.

Travel with me a few more decades into the future. Yes, Ms. Semenya, if you merely undergo gene editing in your muscle tissue to cut the activity of your androgen receptors by fifty percent, we’ll call you a woman, and you can play in the women’s sandbox. Gee, how nice of them: today, she can drug herself and deal with the side effects; tomorrow, she can edit her genome. But certainly she couldn’t just be herself, now could she?

It could go the other way, too. Hey, twelve-year-old girl showing athletic promise, if you can just modify these ten genes, you can compete as a boy! And it’s, of course, not going to affect your ability to have children or nurse or anything like that. Or maybe we start from embryos? We can create our group of athletes: strong, attractive, moneymaking. But of course, the sponsors must be paid back. We wouldn’t want this engineered slave race—oops, sorry, I meant cadre of competitive athletes—to fail to bring riches to their patrons, now would we?

Once science can transcend the idiocy of considering solely testosterone, this world is possible. So, as a Ph.D. biochemist, I am arguing that although looking at gender as binary is ridiculous, binary distinctions in sport are a more ambiguous issue. Is it okay to establish the best metric one can, discriminate against women who fail whatever metric one uses, and ban all use of modification to reach that metric so as not to exclude women from the highest ranks of sport?

If so, then the real problem with the ruling is the part that said that Semenya can compete if she artificially lowers her testosterone levels with medicines. If this is okay, why isn’t all doping okay? I worry about the precedent set by encouraging the use of a medicine with undesirable side effects solely as an eligibility criterion.

Because it sounds like a precedent that will last into the now-seemingly-science-fictional future.