Me, I’m from traditional southern stock.
Dad is a family-history nut. As anyone who considers stock and parentage would tell you, that requires exploring lots and lots and lots of source-trees before you know much.
Hunters (father of father of father of father of father ad infinitum, the easy tree) = Scottish, emig circa 1600-something-or-others. Chased out of Scotland in some flavor of trouble, settled in Virginia.
McMaths (father of mother of father and etc upwind, pretty easy tree) = also Scottish also 1600s settlements
Jennings (mother of father of father, fathers upwind from there) = English, 1600s-1700s settlements
Bowen (mother of mother of father, fathers upwind) = Scottish, some English
Welch (mother of father of father, fathers upwind) = Scottish/English
Butler (mother of father of father of fatherl, fathers upwind) = English we think?
Turner (father of mother, fathers upwind) = not traced to American shore, English?
Farmer (mother of mother, fathers upwind) = Scottish / English we think?
Wright (mother of mother of mother, fathers upwind) = Irish we think?
MacKie (mother of father of mother, fathers upwind) = Scottish pretty sure?
Your basic redneck long-estab southern and/or Appalachian population is often old settlement, did not make it rich in the new world, generally lacks info on ancestry beyond a family bible etc.
The Irish potato famine is better remembered as a cause of immigration but earlier political quarrels esp between England and Scotland circa 1600-1800, but those also gave reason for folks to emigrate, sometimes kind of suddenly.
I know this sounds like I am explaining the very behavior I previously questioned, but I still don’t understand why they’d not assume they were English (if they knew no better) rather than put down “American” which obviously can’t predate 1776.