Royal Blood: Averted, except inasmuch as those who know they’re going to grow up to be rúner are genetically engineered for a laundry list of desirable traits in people who are expected to hold sovereign authority and use it wisely, rarely, and with great caution.
(Of course, given the nature of civilization, it’s not like any of those traits are specific or restricted to the rúner…)
I would guess that a lot of imitators decided to adopt those genes too just because the rúner were using them.
And I don’t seem to recall how the Imperial Couple are selected.
Well, not so much just because. I mean, they’re good, practical genes that strongly promote positive traits. There’s plenty of purely practical reasons to adopt various of them.
Latter about to be answered in a post, because it’s kind of long.