It's... a complicated subject of history. Due to a rebellion that caused some trouble, the empress decided to keep all adult trolls off of the planet. This helped to separate them, limiting the chances that any organized resistance could begin. Meanwhile, from what I know of our history things did not particularly change for the children. You have to understand though, that our life-cycle is somewhat different from humans. We are born as grubs in the brooding caverns. Most grubs are culled, but some manage to pupate into the adult form. Those of us that do begin a series of trials. The survivors are adopted by a lusus naturae, monstrous creatures that live on our homeworld. Each of us is raised by a lusus, and as far as I am aware each of the Trolls here in Vatheon had a different type of lusus.

I hope that was sufficient to answer your question.