One DNA letter can trigger complete sex reversal

This is pretty interesting research. Specifically the fact that it shows how changes in 'non coding' regions of DNA can have such strong far reaching effects.

Also a good reminder that sex is more complicated than people think. XY and XX is not the end all of sex in mammals, it's just the initial blueprint. As can be seen in real life software world too, the implementation(s) can often be much different from spec due to variety of reasons. Real world is messier than simple abstractions. So one must remain humble and be ready to see and interface with the unexpected.

One must qualify the title though imo. It isn't about sex reversal but sex development. They showed how a small alteration to the dna can change development trajectory of the mice embryo into male or female phenotype. This particular research does not yet show reversal in already developed mice. But that would be interesting research path to pursue imo.

... in mice. [0]

[0] https://jamesheathers.medium.com/in-mice-explained-77b61b598...