I have searched around the site and seen several population-related questions, but not one that is getting at what I'm specifically wondering (or that is at least explaining it in a way that my mathematically challenged brain can get around). Apologies if I missed one though.
So I have a kingdom with a population of approximately a million people in 24,000 sq miles. The kingdom has existed for approximately 1600 years. This kingdom is probably analogous, roughly, to medieval Europe in the 1400s. I've worked out that there are 159 noble families within this population. (using this site and tweaking things here and there: http://donjon.bin.sh/fantasy/demographics/)
Due to various events, the nobility is predominately killed off, save for a single child from each family (some families without children and some mishaps meaning not every family), leaving 113 children of the noble class left. The population is basically human for all intents and purposes, but there is magic-type element at play that manifests in one member of this noble class at a time and does not pass directly from parent to child-- it just appears to randomly select a new host within the group when the previous has died.
I am trying to figure out if:
159 noble families is enough that there wouldn't be significant risk of inbreeding through the 1600 year history (safe to assume the number of noble families may fluctuate throughout the centuries, but 159 is the number prior to them being massacred).
And how many individuals would be a part of these 159 families, realistically. Again, overall population is around 1 million.
ETA: second part question removed because it's a moot point and I just blanked on an obvious point in my story. haha