 His father was Giovanni Cavalieri, a court messenger, but there were rumours that Mussato is the illegitimate son of an adulterous union between Viviano Muso and Cavalieri's wife.These rumours arose because Mussato adopted the last name Muso in his early years, probably, though, as tribute to Viviano Muso, who provided protection to the Cavalieri family and stood as godfather to Mussato.By 1276–7 Viviano Muso had died leaving Mussato and his family in a state of poverty.