Ha! Sounds suitably Bakkerian Locke, but depends on whether the Mandate understood the principles of eugenics in the same way we do
Expanding on my thoughts that the Ishroi caste were like the Spartiate rather than Plato's Republic, here is a wiki reference that neatly covers my reasoning on the 'curse of the Ishro'i.
http://en.wikipedia.org/wiki/Spartiate Given that the nonmen were kind of like the Greek gods in their form and passions, I think we can see why their wives would be inclined to play around behind their backs. We even have the example of Cimoira where a high ranked Ishroi's wife got jiggy with Sirwatta, a human slave.
That same instance mentions the Judges of the Ishroi, which sounds like another sub-category within nonman society.
Certainly, we can reason from examples that Quya served in military, administrative, religious, crafting and philosophical/'scientific' roles. It's possible, given the long lifespan of Cunoroi that they might function in these roles at different points in their lives.
Also interesting is the effect of hereditary sorcery. Does this mean that Quya were also comprised of females prior to the womb plague? Did this require both parents be Quya? What was the incidence of the Few amongst nonmen? It certainly seems like they were more common than amongst men. Perhaps 1/2000 rather than 1/200,000 (my rough estimation).
Su'juriot possibly adds more fuel to my theory that being Quya is incidental to the qualities required for rule. Why else the special designation as 'Witch-king'. Surely this serves to differentiate him from a standard king.
