All I have is the perspective of a middle-aged mom... and I agree that you probably shouldn't use a blanket statement here. I've noticed that a few different writing groups I've attended over the years, all comprised of women, haven't had a specific leader. It seems to me that in the case of these writing groups, one woman would take the reigns for a meeting, then another the next week. It was an unspoken thing. Most of the group members acted as leader at one time or another. As a mom, I've noticed that in the younger grades, the groups of my sons' friends would definitely have a ring leader, someone whom the rest of the group seemed to follow. That dissipated the older they got, and now, my sons have friends but no assumed leader; everyone seems equal, with as much say and direction as anyone else. Then again, I'm on the outside looking in. Maybe age and gender play into this?