Background
He was the son of Roger Seymour (born Hatch Beauchamp, Somerset, c 1367-1370, died 1420) by his marriage to Maud Esturney or Esturmi, daughter of Sir William Esturney or Esturmi, Speaker of the House of Commons, paternal grandson of Sir William Seymour (Hatch Beauchamp, Somerset, c. 1342 – 25 August 1391, brother of Lettice Seymour (born Rogaid, Glamorgan, c 1343), wife of Gilbert Gamage and mother of Sir William Gamage) and wife Margaret de Brookbury or Brockbury, and great-grandson of Sir Roger Saint Maur or Seymour, Knight