The original post astonishes me. When I was 12 or so, I thought, "Men are this, and women are that." Then I grew up and realized the world is more complex than that.
The world is not made up of G.I. Joes and Barbie dolls. You seem to suggest that it should be.
Your idea seems to be that men and women each have a distinct, intrinsic nature, from which their proper roles in society can be inferred, en masse. But isn't it reasonable to expect a person to act on the basis of their own nature? If someone wants to do something, such as join the army, then joining the army seems to be in the nature of this person. You would say to them, "But that's not in your nature." I think they should reply, "Clearly it is in my nature, for it is what I want to do." How do you reply to this?
It's a reasonable question to ask. The answer is that masculinity is not only an aspect of the nature of men, but it exists as well as an essence in the sense of it being a quality that has intrinsic value and meaning.
So a man will not only have a sense of his own masculine identity, he will also recognise the existence of a masculine ideal to develop toward, one which brings purpose and fulfilment.
Ordinary preferences and wants do not have this same potential. They certainly do not define our nature as men; if anything, they are to be brought into line (i.e. ordered) according to our efforts to cultivate masculine character.
And the same goes for femininity & women. Women obviously have a feminine nature in the sense that their bodies are more fitted for motherhood than warfare, that women are in general more emotional than men and so on.
But that's not the end of it. Women have the chance to embody the feminine principle in life (to put this another way: to express a feminine essence).
They cannot do this in the role of a combat soldier. It just isn't possible to develop along feminine lines in such a role.
And so a woman who thinks she wants to be a combat soldier has some serious thinking to do. Even if she is at the more mannish end of the female spectrum, and so is drawn more than other women to masculine pursuits, she is choosing a pathway that cannot lead her to an admirable womanhood, i.e. to a womanhood that embodies or expresses that feminine principle of life.