Leonard's surname has been spelled numerous ways, including Carl, Karl, Corl, Corle, Corell, Curl, Curle, Curell, Currel, and Currell, which makes it difficult to track his lineage. There is consensus, however, that Leonard's surname is Germanic in origin. The spelling C-O-R-L-E has been used by the numerous descendants who remained on the family homestead and founded the village of Pavia, Pennsylvania, where Leonard and his wife Mary are buried.

Nothing definitive is known about Leonard's early life. According to his gravestone, he was born in 1755. Leonard may have been born in Germany (perhaps in Lindberg, Bavaria ) or Switzerland, but there is reason to suspect that he was born in Pennsylvania.

Frederick Corle was born in January 1822 in what is now Union Township, Bedford County, Pennsylvanina, the son of Jacob and Elizabeth (Bowser) Corle Sr. Fred grew up on a farm in Union Township, the sixth of  seven children.

Sophia Shull was born on July 5, 1826 in Bedford County, Pennsylvania, the daughter of Jacob and Polly (Russell) Shull. She grew up on a farm in Union Township, the second of ten children.