Kevin, over at The Smallest Minority reports on a book, Born Fighting: How the Scots-Irish Shaped America.  He has this to say about the book:

The Scots-Irish culture is a highly individualistic one, but one willing to follow a strong leader. It has a hatred of aristocracy, but a respect for accomplishment. It’s also an embracing culture – adopt its ways, no matter your background – and you’re an accepted member.

…

If you want to understand the portion of the populace that decides elections these days, I recommend you read Born Fighting. If you’re of Scots-Irish descent, you’ll find yourself nodding and agreeing. If you’re not, you’ll be shaking your head. But trust me on this: James Webb knows whereof he writes.

It turns out those attitudes and personalities are still very visible in the descendants of those people today.

Barbara Scott, my wife, is of Scot-Irish descent (with a last name like that you never would have guessed?).  Reading up on genealogy she found some interesting information on how the Scot-Irish immigrants and the German farmers (IIRC Huffman, a German name, means worker on a small farm.  I grew up on a farm.) who immigrated at the same time into Virginia interacted.  Also of interest is that Barb and I are cousins–about 5 or so generations back one of her relatives married one of mine in Virginia.  We didn’t know this until a couple of years ago.  Anyway the interactions and attitudes of those immigrants is not that much different from Barb and I.  Not hostile but not always cooperative either.  Our communication style is very different and we approach conflict MUCH differently.

Our children’s personalities reflect those differences too.  James is the German.  Kim is the hot-tempered Scot-Irish.  Xenia is mostly German in personality but loves the Scot-Irish culture.

Ry and I have had some all night discussions on the topic of genetics and personality and the results were far more disconcerting that we cared to believe.   Think about it some.