The North-South divide on two parent families

[Igel]

2. Yes. But this isn't predictive.

Just consider the Inuit versus the Algonquians. I'd rather be with the Iroquois, thank you, in 1500.

Or with the Romans instead of the early Slavs. There's a reason for the mass migration in the Wandering of the Peoples in the early Dark Ages.

If it had gone the other way, with the South trumping the North, the claim "lots of social outcomes are better the farther south you are." It's a nice observation but needs to be quantitatively grounded in geography and over time, that's all, and also take into account things like the relatively dry belt at the horse latitudes, availability of food stuffs. Then perhaps a valid generalization is achievable.

This is pretty much all temperate, with relatively similar conditions holding in terms of food, water, education. (No, test scores don't say much about teaching, thank you. They do say a lot about learning. While there's necessarily a connection between the two, they're really different in most ways.)