In this he is mentioned as being seven years of age (i.e., presumably in his eighth year), which again gives us his birth-year as 1475.
(c) September 12, 1484 .-- A Bull of Sixtus IV, appointing Cesare treasurer of the Church of Carthage.

In this he is mentioned as in his ninth year--"in nono tuo aetatis anno." This is at variance with the other two, and gives us 1476 as the year of his birth.
To these evidences, conflicting as they are, may be added Burchard's mention in his diary under date of September 12, 1491, that Cesare was then seventeen years of age.

This would make him out to have been born in 1474.
Clearly the matter cannot definitely be settled upon such evidence as we have.

All that we can positively assert is that he was born between the years 1474 and 1476, and we cannot, we think, do better for the purposes of this story than assume his birth-year to have been 1475.
We know that between those same years, or in one or the other of them, was born Giovanni Borgia; but just as the same confusion prevails with regard to his exact age, so is it impossible to determine with any finality whether he was Cesare's junior or senior.
The one document that appears to us to be the most important in this connection is that of the inscription on their mother's tomb.

This runs: FAUSTIAE CATHANAE, CESARE VALENTINAE, JOHANNAE CANDIAE, JUFFREDO SCYLATII, ET LUCRETIA FERRARIAE DUCIB.