What about XXY people? They usually present as males with lower testosterone levels. Or XYY (these are usually outright males). There's also XXX. We are at a p

What about XXY people? They usually present as males with lower testosterone levels. Or XYY (these are usually outright males). There's also XXX. We are at a point where we have a deeper understanding of human body development than before (not at all complete knowledge though). I don't see a reason not to account for that deeper knowledge in sports. And doing that for natural differences presents an opportunity to not exclude people willingly converting as well, so why not make the most of the opportunity? Sure, all the classes might not be fair as we construct them today, but you know, let's iterate. Gender split in sports comes from a desire to be inclusive in sports: without it, women would be largely excluded from sporting competitions. But the goal is inclusiveness, and gender split is such simply because that was the historical extent of medical knowledge about what influences performance. So whatever we come up with should serve the goal of inclusiveness, strictly increasing it! Otherwise, we'd only get super heavyweight boxing class: too bad those guys never grew past 170cm.