It's called, "Born Fighting", and traces the history of this culture (called the Scots-Irish in the book) from it's origins in the lowlands of Scotland, to America. My high-schooler read it as part of our American History unit. I highly recommend it.
Sowell has written a few books on the subject of Race, culture and migration. I found them facinating. Not page turners to be sure, but very enjoyable.
A few titles on the subject by Sowell in case you are interested.
Migrations and Cultures
The Economics and Politics of Race: An International Perspective
ETHNIC AMERICA: A HISTORY
Race & Culture: A World View
Conquests and Cultures
Migrations and Cultures: A World View
Yeah, except I wouldn't put people like Robert Redford in the same class as George Patton or Stonewall Jackson. People like Redford aren't fir to clean Jackson's or Patton's boots.