Earlier quoted context omitted.
They're describing a difference in sex vs gender. From the linked article: > Gender [...] involves a set of behaviors and norms that shape how men and women act, prescribe how they ought to be, and specify what it means to be a man or a woman > ... Unlike in any other animal, gendered behavior in humans is wildly different across cultures Sex needs a definition too: > Sex appeared to be purely, simply genetic—until 1…
It's funny that many languages don't have this „gender vs sex“ separation. For example in my native language there's just one word to describe man/woman option. Some people try to bend over and invent new terms. That doesn't play well with claiming that somehow this „gender vs sex“ separation is not a new cultural phenomena.
The current usage of "gender" was introduced by American psychologist John Money in the latter half of the 20th century.
It's popularity in common speech was accelerated by "sex" becoming a synonym to "copulation," causing "gender" being used as a polite alternative.
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But how is gender actually defined? Even now, the Oxford Dictionary: "gender: the male sex or the female sex"