 She was born on 29 July 1942 and is the daughter of Marie Joseph Elzéar Foulques, 7th Duke of Sabran-Pontevès and Roselyne Manca-Amat de Vallombrosa.Gersende also descends from James II of England through his illegitimate son, James Fitzjames, 1st Duke of Berwick, through her maternal grandfather's mother, Geneviève de Pérusse des Cars.Her maternal grandmother was a direct descendant, in the male line, of the Bonapartist Marshal Jean Lannes.