Gene editing moved from therapeutic to optimization sometime in the mid-21st century, and by the time anyone thought to regulate it, the results were already inheritable. In the Sprawl, genetic modification created permanent, inheritable biological castes that even wealth can't overcome within a generation. Unlike augmentation-based prejudice (ST #13, which is removable), genetic modification is written into DNA — passed to children, compounding across generations. The elite don't just have better augmentations; they have better biology. Their children are born faster, smarter, more resilient, with immune systems designed by committee and lifespans measured in centuries. The "naturals" — those whose genomes reflect the unedited lottery of reproduction — are a permanent underclass, not because they lack talent but because their ceiling is another caste's floor.
The uncomfortable question: is this eugenics? The answer is yes, obviously. But the results are objectively, measurably superior — longer lives, fewer diseases, greater cognitive capacity. The Genome Divide isn't between good and evil. It's between those who believe equality is a right and those who believe optimization is a duty. Both sides are sincere. That's what makes it devastating. Speciation risk — the biological divergence between castes becoming so extreme that interbreeding becomes difficult or impossible — is a quiet, unspoken horror that geneticists discuss in closed forums. The question isn't whether humanity is splitting into subspecies. The question is how many generations until the split is irreversible.
The split has a terminus, and the terminus arrives ahead of schedule. The cognitive speciation — the point where the deepest-optimized minds stop being able to compress their thoughts across the gap to the rest of the species — arrives roughly a century before the reproductive one. This is the Crossing (the-crossing): the thread's ninth dimension, where the Divide stops being a ladder of degree and becomes a horizon of kind. The crossed don't persecute the un-crossed; they outlive them in advance, with the gentle, distracted kindness you give a dying grandparent. And the un-crossed — natural-born and ordinary-designed alike — become the Remainder Generation (the-remainder-generation), the last fully-human cohort, archivists of a species writing its own epitaph. It is the first axis of prejudice that produces no slur, only a blessing said flat at a funeral: gone-ahead.