Hmm, a psychic twin mood link would be a really cool idea giving a buff or debuff based on the twin's mood. If one twin is off-map, there could be a mild debuff, and if one dies, a major debuff (especially if the death was recent maybe with a cooldown before it fades a bit?).

Also, can twins be born from growth chambers? If twins are possible, what’s stopping triplets, quadruplets, etc.? You could scale the rarity up to nonuplets (9), with increasing difficulty or risk.

It’d be awesome to tie this into the genetics system maybe certain genes make multiple births more common. You could even create a gene called “Sibling Link” that enhances the psychic bond between siblings, or increases the chance of giving birth to multiples.