Mary Seymour was the daughter of Jane Seymour, the third wife of King Henry VIII of England, and she was born in 1537. After her mother died shortly after childbirth, Mary became an orphan and was placed in the care of her maternal uncle, Edward Seymour, the Duke of Somerset. Mary's life was marked by uncertainty, as she was a child of royal lineage but lacked a stable position in the court. She was eventually married to Thomas Keyes, but they had no children. Mary Seymour's fate remains largely unknown after her marriage, and she disappears from historical records.