It occurs to me a big advantage of having two parents in the picture, as well as grandparents, aunts, uncles, cousins and the like, is that that child emerging into adulthood has many models, and can adopt, consciously or unconsciously, it doesn’t matter, the models that fit them best.
I was thinking of my own children. They combine, I think, the best aspects of both of us. They have my emotional intelligence, passion and curiosity, and their mothers stability. I am many things, but stable is not one of them. Self regulation, obviously, is something I am still working to master.
Conversely, if you only have one parent in the picture, I suspect the temptation to draw from mass media becomes nearly impossible to resist, and movies and music and TV are largely lies.
A richer society would be one more geographically stable. I think we all sense this. There is a time and many reasons to go see the world. But it is important to be from somewhere, and from people you can name.