Here's a rare song by a twelve or thirteen year old Charles Hardin Holley, later better known as Buddy Holly. It was recorded in their family home at 3315 36th Street in Lubbock, Texas sometime in 1949. His voice at the time hadn't changed yet, and the vocals can be mistaken for those of a girl.
His guitar playing is far from childish though; check out the solo between 1:09 and 1:30 in the song.
(The video says he's 13 or 14 at the time, but I've double checked the recording date, and he was born 09/07/36, putting him at 12 or 13 here. )