Yep. Glatthaar discusses this in
General Lee's Army:
Southerners also claimed superior breeding. They argued that they descended from Virginia cavaliers who themselves were descended from Normans. Yankee ancestors descended from Saxons and after them the Puritans. In fact, few Southerners had cavalier lineage, and intermixture among Normans, Saxons and other peoples over dozens of generations had diluted any Norman blood that pulsed through their veins. Nonetheless, they believed it so. No one should have been surprised, they asserted, that their superior breeding and superior culture and upbringing would produce superior soldiers who could overcome Yankee advantages in manpower and material.
It was a self-deception based on an imagined "heritage." My own view is that the Celtic roots of the South are today being overstated in a similar way. (And I say that as a descendant of at least one group of Scots-Irish Confederates.) All things Scots, especially, are going through a resurgence in popular culture, so there's lots of tendency to hitch onto that, and make any and every connection more significant than it probably was, especially when many of the Celtic-descended southerners of 150 years ago were themselves several generations removed from the wind-swept moors and lochs of old Caledonia.
I personally blame this mess on James Doohan, Mel Gibson, Jim Webb, and Groundskeeper Willie.