The military is a meritocracy. It's an up or out. It's shaped like a pyramid.
The military tends to be a traditional place. Traditional culture, traditional men are often attracted to serving in the military.
I think the culture is changing. An example of that is that the commanders truly want the very best person for the job regardless of gender.
I can't tell you how many couples I know where the husband and the wife are both in the military and have deployed together, and they've got kids, and so I think times have changed and gender roles have blurred when it comes to the military.