I believe your personal experience may be narrowing your view.

I have a similar family experience with drastically different outcome. Including ties to your idealize Iowan people (born to Iowan w/ Iowan grandparents, great grand parents and so on back to Jamestown for a couple), who are simply that, just people. Most Iowans come from late 1800 immigrants, many from East Europe. Some of my Iowan family lines are outliers in terms of origin (first families), but there is at least one from 1800 East Europe that I know of. If you moved on from British history to American History, you would better understand the real mixing of immigrants/cultures, and that is distinctly American. They did not all stick to their kind, as it were.

Some recent family has integrated with Asian immigrants and they are more "American" than some of my Iowan families in-laws that have been radicalized into anti-American values, much to my Iowan families horror. That has nothing to do with "cultural attitudes" etc, and everything to do with living in internet bubbles.

Iowan's I know and come from are blue through and through--Union loving gun toting Democrats. Most of them have kept their values, some have let Fox "news" take that thinking over for them.