 Da Mosto is the younger son of Count Ranieri da Mosto and Contessa Maria Grazia Vanni d'Archirafi, who comes from a very old Sicilian noble family who are the Dukes of Archirafi and include many noted Italian diplomats and bankers.A Roman Catholic, da Mosto took his first Holy Communion in the crypt of St Mark's.A few years later, he received the sacrament of Confirmation from the future Pope John Paul I.

Da Mosto lives in his family home in Venice, with his South African-born wife Jane, his four children, and his parents.