Gender norms are reflection of society expectations.
Society expectations evolve/change with economic and war conditions affecting a particular society at that time.
Those things, unfortunately, go in waves.
So we can pick different parts of history and we will likely see 'gender norms' are being adjusted for the particular environment at that time period.
On top, there are biological projections, and genetic predispositions that are projected on 'gender norms'.
Things that 'change less' are genetic traits and biological differences.
Combining economics/war conditions, with genetic traits + biological differences, creates a sort of 'superposition' that we are observing.
As a society, it makes sense to accommodate the desire of individuals, but not force people into particular choice.
Accommodating a variety of legal choices, is what we should be striving for, rather than trying to influence a particular path.
It is sort of like trying to introduce new type of species (animals or trees) into a new environment -- and expecting that we know about the ecosystem, to predict the effects of invasion.
Most of the time, with our current knowledge and prediction capabilities -- we fail.
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Which is why, I think accommodating choices (and not predicting or promising outcomes) -- is what we should be doing.