Charles never married. He is listed with his brother William in the 1860 census, as age 33, and with his brother James in the 1880 census.

His middle name should not be taken to indicate a relationship to any other Pettit with the same pair of given names. It would represent being named after the fictional character Charles Grandison, who also inspired the name of the influential revivalist preacher Charles Grandison Finney (1792-1875). (A generation later, boys named Charles Grandison would probably be named after Finney, but in 1826 Finney, while having begun his ministry, would not yet have been well known.)

See these articles:

http://en.wikipedia.org/wiki/Charles_Grandison_Finney

http://en.wikipedia.org/wiki/The_History_of_Sir_Charles_Grandison