 By birth he was to be the successor of his father; Prince of Venafro, Venetian patrician, Marquis of San Martino, Count of Celano and Baron of Pescina.However, he was also a nephew of Cardinal Alessandro Peretti di Montalto and a great-grand-nephew of Pope Sixtus V. As his father's only son he was urged to marry to continue the family line.He chose the "Princess of Cesi" but his father disapproved.