Son of José António Pereira de Eça O'Neill (b. Lisbon, ca 1890, d. Lisbon), a Banker, and wife Maria da Glória Vahia de Barros de Castro (b. 17 Mar 1905, d. aft Oct 1989), and a paternal grandson of illustrious Portuguese Writer, Poet, Conferencewoman and Journalist, known by the name of Maria O'Neill, of Irish remote descent, who was also a Spiritualist, Member of the Superior Deliberative Council of the Spiritualist Portuguese Federation and the Editorial Office of the Magazine Espiritismo.