It is a known fact that Seekers of the sun tribes pretty much work like lion packs. The dominant male assumes control over the tribe and mates with all the females within. Sometimes there's more than just one male, but it's rare and usually they are brothers.

How do lions avoid inbreeding with such a system? Simple, as soon as male lion cubs become big enough they get kicked out of the pack. Then some of them become strong and challenge the dominant male of another pack to become the new leader.

But ostensibly... that's not how it works for the seekers of the sun.

From the U tribe quests in the forgotten spring we known that not only male adult miqo'te are allowed to stay in the tribe, they are even supposed to succeed their father!!

But wait... if they succeed their father, doesn't that mean that they'll mate with their sisters then? Is that how it really works?!