Gideon Welles, the son of Samuel Welles and Ann Hale, was born on July 1, 1802, in Glastonbury, Connecticut.
His father was a shipping merchant and fervent Jeffersonian; he was a member of the Convention, which formed the first state Connecticut Constitution in 1818 that abolished the colonial charter and officially severed the pre-American Revolution political ties to England.
In contrast to the Fundamental Orders of Connecticut, the successor constitution of 1818 provided for freedom of religion.
He was a member of the seventh generation of his family in America.
His original immigrant ancestor was Thomas Welles, who arrived in 1635 and was the only man in Connecticut's history to hold all four top offices: governor, deputy governor, treasurer, and secretary.
He was also the transcriber of the Fundamental Orders. Welles was the second great grandson of Captain Samuel Welles and Ruth (Rice) Welles, the daughter of Edmund Rice, a 1638 immigrant to Sudbury and founder of Marlborough, Massachusetts.