Lots of people question about how the pegasi society works, since it seems to be the least known about. Its shown in Hearth's warming eve it is shown that the pegasi was a military type fraction in the older days, oddly enough this reminded my of the Spartans. If we are to consider that the pegasi society was similar to the Spartan's then it would also explain why we rarely see pegasi with their parents, as Spartans sent their children away at a young age to train to be soldiers. Of course the pegasi don't seem to be an army anymore, but the principal might still stand but instead of learning to fight they go to flight camp. Now we do see some pegasi with their parents throughout the series, and I belief this is because these pegasi have split off from the old ways completely, as I also belief the events in MLPFIN is taking place in a major changing point in pony history. So yea thats what I think about the pegasi, they are the Spartans of equestria.