O'Leary grew up in modest conditions in the single street village of Carrigaline, County Cork, Ireland.
By 1616 his father was living in Carrigaline, Ireland, where Gookin probably spent his childhood, later being sent for education to England.
David won his first Carrigdhoun Junior Hurling Championship in 2007 where he played wing back on a team which defeated Ballymartle in the final in Carrigaline in which Cian Quigley also had a storming game.