Of Rolling Stone's top 100 singers, 28 are white male Americans. The interesting fact is that 13 were born in the South. Even more interesting, most of these Southerners grew up poor. Elvis Presley, the third best singer on the list after Aretha Franklin and Ray Charles, is a good example. His father was a sharecropper and a truck driver.
The vast majority of all the white males have English, Scottish, and/or Irish ancestries. The only men I found with some German in the family line are Bruce Springsteen, Greg Allman, Axl Rose, and Steven Tyler. While Italian Americans like Frank Sinatra dominated big band music, the only vocalists with some reported Italian blood that made this rock-dominated list are Springsteen, Tyler, and Frankie Valli. For such a small group, Jews did just fine with Bob Dylan, Lou Reed, and Art Garfunkel.
Why so many white southerners? Well, popular music requires singers with soul, naturalness, and unschooled talent, and Scots-Irish men of humble origins seems to have it. I might be tempted to suggest that people with lower average IQs (e.g., blacks) tend to be more in touch with their instincts, but Jews contradict the idea. (Plus, I imagine that successful singers have above average IQs relative to their group). Another possibility is that there is greater extraversion among southerners, an important trait for performing.
Southern men also seem to have voices that are more resonant and lower. This isn't valued particularly with many types of popular music, but country western fans are drawn to it. Buddy Holly didn't have it, but it sure helped Johnny Cash and George Jones.
Women from the South didn't do too badly either. Of the nine white American women on the list, three were southerners: Patsy Cline, Dolly Parton, and Janis Joplin. All three had a lot of passion, and Cline even had resonance like the men.
Keep in mind that so many of these men made a list that was chosen by music elites in places like L.A. and New York. People there are not known for their love of southern whites.
I guess "white trash" folks are good for something other than cannon fodder.