He was of of the Duffry, a district in Temple-shanbo, co. Leinster.

Douglas Richardson: "As for the parentage of Robert de Quincy, it is uncertain where he fits into the Quincy family tree. On chronological basis alone, I would assume that Robert was the son of Saher de Quincy, of Long Buckby, co. Northampton, by his wife, Maud de Senlis. This couple had two identified sons, Saher, who evidently died without issue, and Robert, the eventual heir, whose career is well documented. That leaves the possibility that Saher and Maud may have had two sons named Robert. Two sons named Robert actually occur in a later generation of the Quincy family, so that possibility needs to be considered."