It's such a closed system, they can even track when new genetics were introduced in the "early 1900s" by visiting Russian ships.

Heading towards inbred by an aging declining population.

I would suspect it's like a lot of small towns: Inward facing, busy keeping their own share of limited local resources from being grabbed by other locals.

If an individual can't deal with that, I suspect they've moved off the island, or their genetics will be culled from the population.