There have been essays written by smarter and more eloquent people than I about healthy male culture. The bottom line is that old men are instrumental in the development of young men. When there is a lack of old men the young men have a tendency to turn "feral". It has been argued that to have well behaved young men you need dangerous old men, and I believe this is true.
This is a simple, even "Darwinian", concept. Successful men have survived their environement, they have achieved a level of success that gives them the authority of experience. It is the whole "been there, done that" factor.
The US Army and Marine Corps turn young men into old men very quickly. Not only in body, but in the mind and soul. The amount of "experience" that one can amass while serving is intense. And experience is what seperates the old men from the young men.
I don't know about or understand the processes that women have to bring up a girl into adulthood. Maybe there isn't a need for dangerous old women to keep the young women in line. As an observer I think that girls don't go "feral" but they go "tomboy" without the feminizing influence of a successful woman. I don't use the word "feminizing" lightly, it is a magical thing full of power and mystery. But that is enough on a subject about which I know next to nothing.
Soon I will be in the last year of my 20's, and I'm guessing that 30 is the gateway year into middle age. By the norms of the Army a Lieutenant is supposed to be a young man 21 to 23 years of age. The War on Terror opened up a lot of officer slots that prior service NCO's like myself volunteered to fill. Right now we have the largest population of OCS graduates filling the junior officer ranks since Vietnam. One could write a dissertation about aftermath of Vietnam, transitioning to an all volunteer force, and the officers who were commissioned through OCS such as Gen. Tommy Franks.
Which leads to some interesting questions. When my peers and I start retiring in a decade how will we have affected the Army? Will we leave behind a leadership or competency gap similar to the mass exodus of experience that happened after the first Gulf War (and Vietnam, Korea, and WWII)? Or instead will we have brought up and developed the young men to take our place? Will the influx of prior service officers be a force for innovation or will it stifle progress? There are a lot of questions running around my head that simply cannot be answered now. My suspicion is that the type of people who become officers and NCOs simply will not allow any one generation of leaders to become the linchpin of organizational competency. After all, the military has more experience developing young men into competent leaders than any other organization I have ever encountered.