What I meant to add to the last post was that indeed, the Mennos and Amish by definition HAVE to be cousins even 6-7th generation abck, or closer. I often ask the ones that I know are related, "Oh, isn't so-and-so your cousin?" And they say, "Naw." That is because they are 3rd cousins. I think they only count 2nd cousins as being related. A very dangerous mentality. Or they will say "we are not related that we know of", even though they share a VERY common PA Dutch name. (Not names that the "rest" of the people out here have, and these are people in their own denomination!!! So perhaps that is where the trouble lies. They need to see how close is close.
The forbidden degrees usually only include 1st cousins - plus one more "for luck".
That's usually plenty where the cousinships aren't steadily accumulating . . . and they usually don't. Under normal circumstances even in a small Southern town the most you'll get in a marriage is double cousins on two branches.
Although when my dad was a kid in Rome, GA, he was sitting on the levee with a bunch of his schoolmates, maybe 8 or 10 guys (it was a boys' school), and they realized after some desultory conversation that they were ALL related.
Of course they almost all looked elsewhere for their brides. Dad married a girl whose parents were both from Augusta GA. We've never found any cross-matches in their family trees, and I have a solid eight generations now on ALL branches - some a good deal further back.