@
Torsten It's a variation, like nearsightedness. Unless you're willing to call
all variations "defects" then you need to explain to me why you think variations that tend to make people into world class athletes are "defects."
The natural world is far more complex than what they taught you in elementary school.
The Woman Who Gave Birth Despite Most Of Her Cells Having XY Chromosomes
In 2008, doctors reported a curious case report about a woman who gave birth despite the majority of her cells having XY chromosomes, typically held by people who are biologically male.
A woman from Croatia sought medical attention when at 17-years-old she had not yet developed breasts, nor had her first period. Upon examination, the doctors didn't find much out of the ordinary, aside from the absence of these signs of female puberty...
... Though her blood was found to be 46,XY, samples taken from elsewhere around her body were not so. Cells in her skin were found to be 80 percent 46,XY and 20 percent 45,X, indicating Turner Syndrome with mosaicism...
... More interestingly, her ovaries were found to be predominantly 46,XY (93 percent 46,XY and 6 percent 45,X), i.e. her ovaries contained chromosomes typically found in the cells of male individuals.
https://www.iflscience.com/the-woman-who-gave-birth-despite-most-of-her-cells-having-xy-chromosomes-61747