Gist was born in Baltimore, Maryland (one source says Reisterstown, Maryland), the fourth child of Thomas and Susannah Cockey Gist. Thomas Gist's father, Captain Richard Gist (1684-August 28, 1741), was the surveyor of Maryland's Western Shore and one of the commissioners who laid out Baltimore Town in 1729. Richard Gist's father, Christopher Richard Gist (1655 or 1659-Feb. 1690), was an English emigrant who came to the Province of Maryland before 1682 and settled in "South Canton" on the south bank of the Patapsco River. Christopher Richard Gist married Edith Cromwell (1660–1694), who is believed to have been a relative of England's Lord Protector.