Is there any historical basis for the idea that rural southerners often became intimate or married their own kin?

by tanto_le_magnificent

What basis historically is there for the suggestion that Bible Belt states routinely are incestuous to the point where jokes are often made of it? Was or is it that common and is there any evidence or data?

sunagainstgold

I'm not sure it's a perfect fit, but if you're interested, I have an earlier answer about the development of the incest stereotype in Appalachia and the Ozarks through regional literature and its national audience:

In popular culture and meme posts there's a stereotype correlating living in Southern states and incest. Is there any historical reason why this stereotype is a thing? Why aren't Northern American states associated with this stereotype instead?