[3] Her father, Ernest Thompson Seton, was Boy Scouts of America co-founder, naturalist, and author.

[4] Her mother was Grace Gallatin Seton Thompson, an author, suffragist, two-time president of the National League of American Pen Women, and founder of the Campfire Girls.

[2][10] Three of her books are classics in their genre and continue in their popularity to the present: Katherine (1954), the story of Katherine Swynford, the mistress and eventual wife of John of Gaunt, and their children, who were the direct ancestors of the Tudors, Stuarts, and the modern British royal family; Green Darkness (1973), the story of a modern couple plagued by their past life incarnations; and The Winthrop Woman about the notorious Elizabeth Fones, niece and daughter-in-law of John Winthrop, the first governor of the Massachusetts Bay Colony.

In 2003, Katherine was chosen as Britain’s 95th best-loved novel of all time in a nationwide poll conducted by the BBC.

[12] Her 1962 novel Devil Water concerns James, the luckless Earl of Derwentwater and his involvement with the Jacobite rising of 1715.

Seton said that her greatest debt of all was to Amy Flagg of Westoe Village in South Shields, her father's birthplace.

[6] Two weeks later, Seton married investment counselor Hamilton "Chan" M. Chase, whom she had had an affair with.

[15][6] Seton died of heart failure at the age of 86 on November 8, 1990, at Sea Rune in Old Greenwich, Connecticut,[10][11][3] and was survived by Pamela and Clemency, five grandchildren, and a great-grandchild.