Grant was born on the island of Luzon in the Philippines to Michael Grant, 12th Baron de Longueuil, and Isabel Padua; her family moved to the United Kingdom when she was a baby, and she was raised in Nottingham, England. She is of Scottish, French-Canadian and Filipino descent. She is related to the British royal family through her grandfather, the 11th Baron de Longueuil, who is second cousin to Queen Elizabeth II through the Bowes-Lyon family.Burke's Peerage, Baronetage and Knightage, 101st edition, ed. L. G. Pine, Burke's Peerage Ltd, 1956, p. 2389
