See my other comment in this thread about anthropologists dichotomizing societies based on nuclear vs extended families. In short, it’s orthogonal to the issue.
Long lasting societies have a larger formal weave based on outworking and out breeding, formally moieties in the indigenous peoples of North America, Australia, Indonesia and elsewhere.
A single family unit alone is insufficient and historically cycles members in and out over half a generation through marriage and fortune seeking.
I've seen your other comments and they have that kind of first order depth expected of a simple thought and looking things up quickly on a phone.
Here's a very shallow introduction to a family of systems with many variations that lasted some 70 thousand years keeping bloodlines clean: https://en.wikipedia.org/wiki/Moiety_(kinship)