Uniquely, perhaps not, I'm not sure I said that. However, we have had sexual reproduction for 2 billion years. There can't be many features that differentiate us one from another that are as old, and as thoroughly baked in to us. What are the core things that a human needs to do to survive? Eat, find shelter, and have sex. Recognising, and finding important, the difference between men and women has been critically important, and has been critically important for millions and millions of years. It is very clearly baked into brains across the animal world from penguins to elephants. Very frequently you see differences in behaviour, and differences in role in the animal world, just as you see it with us. This again is not surprising because for one thing there is a function that only females can perform. For another, in times of threat, the value of the sexes is not remotely the same as one another.Indeed, and I agree that it would be incredible if this was not the case. It would also be incredible if these differences were uniquely tied to sex differences.
What other cultural architypes are you thinking of that are remotely as significant? Are there any that you can detect the differences between in the behaviour of new born babies, that we have different hormones and so forth to steer? Thinking that society can make these differences inconsequential is like thinking society could regard food as optional. Sure there are cultural rituals around food, but they are build upon a basic physical reality and necessity, just as gender is.
Believing all this stuff is optional, and arbitrary is like believing in breatharianism.
There is a saying you see going around on the dissident right that comes from Spengler:
“When the ordinary thought of a highly cultivated people begins to regard 'having children' as a question of pro's and con's, the great turning point has come.”
He is saying that when having children isn't just something you assume you are going to do, the civilisation is doomed to collapse. I think that pretty easily extends to people acting as if they don't know what men and women are. There are core tasks that civilisations need to do to survive, and we seem to have decided that one of them is optional.
Sure, we live in a decadent age where people have ridiculous beliefs that in harsher times would have got them slapped round the head and made to do something useful. Trans stuff is just an even more silly, decadent belief on top of previous only marginally more sensible ones. They are peacocks tails. These things aren't so bad when it's just a fringe aristocratic fad. If it spills out though, it's like if the Chinese had decided they were going to normalise foot binding, and you'd had peasants tottering about the fields.It's just that this seems to be an unpopular view among those here who are skeptical of trans rights. I have certainly received quite a lot of pushback from this contingent when I suggest that the brain might be gendered in this sense.