House of Sforza
The illegitimate son of Costanzo I Sforza, he was a member of the powerful House of Sforza, in the line of Pesaro and Gradara (the Milanese line held the Duchy of Milan at the time). At the death of his father in 1483 he inherited the lordship of Pesaro and Gradara, though he was only seventeen and so the lordship was initially ruled by his father's widow Camilla d'Aragona as regent.