In colonial America, the status of the mother—free or slave—determined the status of the child. Sally Hemings's father, John Wayles, was white but her mother, Elizabeth Hemings, was a mulatto slave— the child of a white father and a full-blooded African mother. Elizabeth Hemings was Wayles's slave from birth, and after the death of Wayles's wife, she became his mistress. Together they had six children.

Wayles died in 1773, the same year Sally was born a slave. Sally, her mother, and her five siblings (along with about 125 other slaves and 11,000 acres of land), were inherited by Martha Wayles Jefferson, wife of Thomas Jefferson (then a wealthy Virginia planter). Sally Hemings was Martha's half-sister, both having been fathered by the same man. Since Martha was born in wedlock, she had rights to the family estate. The Hemingses were brought to Monticello, Jefferson's Virginia...