Her mother was also her uncle, DNA test.

[NullTuples]

25. Not unheard of, but nobody looked prior to maybe a decade ago.

There have been several published papers on women who successfully carry a pregnancy to term and turn out to have XY chromosomes.

One was assigned female at birth, went through a typical girl -> woman childhood and puberty, got married, had a child and then was found to have XY chromosomes. But the really interesting part is that her daughter also has XY chromosomes.

Before maybe 8-10 years ago, chromosome testing was expensive. So if someone gave birth, it was simply assumed a karyotype test would come back XX.
But since then, it's become much, much cheaper so more testing is done. And it turns out that it's unusual, but now well documented that a woman can have XY chromosomes.

Naturally, these last ten years or so is also the time period in which Republicans and other conservatives have tried to appropriate concepts such as "follow the science" without actually doing so. Because the science is so very inconvenient for many of their now-bedrock assummptions.