i bet the soleil twins are lucky that they were born as a highblood - if they were a low/mid-lowblood they'd probably be executed for being "deformed" or whatever - twins are rare in humans, but aren't they like, astronomical in trolls?

They don’t necessarily need to be that astronomical- Specially knowing the Mother Grub lays like a LOT of Troll Eggs and a lot of them don’t make it out of the Brooding Caverns, something tells me there’s more Twins we know of.

This is a big misconception, however, the thought that ALL MUTANTS in Alternia are fated to be culled. Karkat was bound to be culled if they found out his SPECIFIC Mutation, because it made him the lowest of the low, he was entirely outside of the Hemospectrum. The Sufferer had it even tougher because back in the day there weren’t even Crimson Blooded Lusii to take care of him, forcing the Dolorosa to protect him and raise him.

But Sollux is a Mutant as well, remember? And Equius is said to be freakishly strong even for an Indigo. Honestly with what we know about Troll Reproduction, and seeing them have 12 different Blood Colors and an entire sub-species of Seadwellers, it’s obvious the Troll Genome is incredibly volatile and prone to Mutation. But as long as this Mutation isn’t considered a hinderance? Say, an odd number of limbs, lacking eyesight (And not having a cool Dragon Mom to teach you how to unlock Synesthesia), that kind of things would be grounds for Culling. There’s no reason to Cull someone for having Psiionics that can be used to power a Spaceship, or for being extra-powerful, and I don’t see why being born from the same Egg would be any different.

What I’m trying to say is, this is Alternia’s system in a nutshell.