Dominic was born to a Norwegian father and an Irish mother in England. Dominic and his family relocated from England to Bondi, Sydney, when Dominic was two years old, and later to the Western Suburbs. After attempting landscape gardening, he chose to pursue acting after seeing the war film Platoon (1986). The acting was an unlikely professional choice for him because of his working-class upbringing, so he didn't pursue it until later. He attended The Australian Theatre for Young People (ATYP) and subsequently the Western Australian Academy of Performing Arts, where he met his future wife Rebecca and studied under Hugh Jackman.