In the '30s, brother duets were common in country music: Among the better known were the Monroes, the Delmores, the Dixons, and the Carlisles. Bill and Earl Bolick, who in 1936 were ready to make their first recording, followed their producer's suggestion that they should be different by avoiding the word "brother." From "Blue Ridge Mountains, Land of the Sky" they took two words and named their act. But the Bolicks would have been different without the new name. Their intricate yet simple harmonies, their perfectly matching voices, and their unadorned mandolin and guitar instrumental backing set them off from the competition, so much so that two generations of subsequent duet singers echo them, some without realizing it. The Everly Brothers and the Louvin Brothers, themselves recognized as exceptional vocal duets, acknowledge the influence of the Blue Sky Boys. In the '50s, when tastes in country music changed drastically, the Blue Sky Boys retired from music rather than forsake their love of old mountain ballads for the uptempo popularity of electric instruments, drums, and honky tonk. In the '60s they were coaxed to come out of retirement, playing an occasional college date during the hootenanny phenomenon and recording albums in 1963, 1965, and 1976. Born and raised in East Hickory, NC, Bill and Earl Bolick -- the fourth and fifth of six children by deeply religious parents -- learned how to harmonize by singing hymns and gospel songs at home. Bill learned how to play guitar and banjo from his neighbor, teaching Earl in the process. Earl had been given a mandolin, but he preferred guitar, so the two brothers switched instruments and began performing as a duo. Bill also performed with another local group, the Crazy Hickory Nuts, who happened to land a radio spot in...