The Big Sea: An Autobiography by Langston Hughes:
I am brown. My father was a darker brown. My mother an olive-yellow. On my father’s side, the white blood in his family came from a Jewish slave trader in Kentucky, Silas Cushenberry, of Clark County, who was his mother’s father; and Sam Clay, a distiller of Scotch descent, living in Henry County, who was his father’s father. So on my father’s side both male great-grandparents were white, and Sam Clay was said to be a relative of the great statesman, Henry Clay, his contemporary.
On my mother’s side, I had a paternal great-grandfather named Quarles—Captain Ralph Quarles—who was white and who lived in Louisa County, Virginia, before the Civil War, and who had several colored children by a colored housekeeper, who was his slave. The Quarles traced their ancestry back to Francis Quarles, famous Jacobean poet, who wrote A Feast for Worms.