Even if there are some average differences in how men and women tend to behave, there is still a lot of overlap,
Not when it comes to consumerist, employment, special interest & life choices where vast differences are measured in what is fundamentally the biggest parts of peoples lives.
More importantly, behaviour doesn’t determine sex category, people of either sex can show a wide range of traits, so noticing patterns is not the same as defining what someone is.
Same with biological reproductive traits. Individuals vary in morphological, hormonal & genetic characteristics that can be sexually ambiguous in outcomes they are socially perceived.
so behaviour is not a reliable way to define what someone is.
That's why self-identification matters. People come in all different mosaic forms that don't strictly meet social categorisations so its ultimately upto them to decide who they are. While I appreciate the structural necessity for reliable methods of assigning people to categories that doesn't also mean we get to tell them who they are. Only they can. Self identification gives an individual the power to define their own beliefs or identity (which is a core human right) rather than having it assigned to them by others or by institutions .
And let's not forget freeing women from the limitations of being defined by their reproductive traits was a necessary part of how feminists advocated for their self determination.
We also tend to recognise whether someone is male or female instinctively, and this is not really based on behaviour.
A naturalistic fallacy/is ought problem.