Well, I can't say that I've encountered any so-called "sorority-like or fraternity-like" groups during my years in high school (which, by the way, was some time ago).
The only thing that was going on during those days (in the 80's) was the little "cliques" around school and they usually were comprised of people who hung together since kindergarten.
I think that back then, most of us had the opportunity to feel as if we "belonged" without having to commit to degrading or juvenile activities. We didn't haveto result to wearing the same things. There was no "special color or name" that we gave ourselves. And our reasons for spending time together was basically because we were true "friends". I believe that most kids these days don't have that luxury. They don't really know what true "friendship" is. My best friends, clique, sisterfriends---whatever you want to call them----are my friends to the end. Today most of these "sorority-like/fraternity-like" groups in high schools are basically modern-day GANGS. There is no purpose. There is no mission. There is no meaning. There is no true friendship.