While it is tempting to suggest that he was the younger brother or other relation of the much more famous Costanzo Festa, since they were from the same region, had similar musical acumen and both wrote madrigals, no direct evidence of this has emerged.
Sebastiano first appears in the record in a manuscript copied between 1516 and 1519, possibly as the copyist: the document contains motets both by himself and Costanzo.
[1] He lived and worked in Rome in the early 1520s, with the Genoese aristocrat Ottobono Fieschi as his patron, and he worked with other musicians connected with Pope Leo X. Costanzo Festa had been a singer in the Sistine Chapel choir since 1517, so both Festas may have come to Rome at approximately the same time.
[1][2][3] These works, simple as they are, were influential on other early madrigalists such as Philippe Verdelot, who produced his first madrigals around the same time or shortly after Festa.
Claudin de Sermisy, the French chanson composer, even based a parody mass on it – a common fate for a "good tune" in the sixteenth century.