No parents. A troll is raised by a lusus naturae, or lusus for short, which holds the role of custodian for them. After a young troll makes it through the Trials in the Brooding Caves, a monster adopts them, you see. Mine was this big badass crab thing - he was taller than me, even.

But if you want to hear the full details on troll romance, I'll lay them out right now. I can make a diagram afterward if you want, too.