Gesualdo's family had acquired the principality of Venosa in what is now the Province of Potenza, Southern Italy, in 1560. He was probably born on March 8, 1566, three years after his older brother Luigi, though some sources have stated that he was born on March 30. Older ones give the year of birth as (c.) 1560 or 1561, but this is no longer accepted. A letter from Gesualdo's mother, Geronima Borromeo, indicates that the year is most likely 1566. Gesualdo's uncle was Carlo Borromeo, later Saint Charles Borromeo. His mother was the niece of Pope Pius IV.