Jane, the daughter of Sir John Seymour and Margery Wentworth, was most likely born at Wulfhall, Wiltshire, although West Bower Manor in Somerset has also been suggested. Her birth date is not recorded; various accounts use anywhere from 1504 to 1509, but it is generally estimated around 1508. Through her maternal grandfather, she was a descendant of King Edward III's son Lionel of Antwerp, 1st Duke of Clarence. Because of this, she and King Henry VIII were fifth cousins. She also shared a great-grandmother, Elizabeth Cheney, with his second and fifth wives, Anne Boleyn and Catherine Howard.