Hélder Manuel da Terra Fragueiro Marques Antunes was born on 6 July 1963 in Angra do Heroísmo (in the parish of Nossa Senhora da Conceição), on Terceira Island, Portugal, to Armando Manuel Marques Antunes (from Torres Novas, Ribatejo) and Carolina de Vasconcelos da Terra Fragueiro (from Horta, Faial). Antunes grew up on the Lajes Air Force Base, on Terceira Island, where his parents and much of his family worked as part of the Portuguese Air Force.
A year after the Carnation Revolution (25 April 1974), Antunes and his family left Portugal for the United States, settling in Rhode Island. They lived there until 1984, when the family moved to San Jose, California, where Antunes’ father went to work for Lockheed Martin on the Hubble Space Telescope project.
Antunes has three children and two grandchildren. His daughter, Francesca, lives in Idaho with her husband and family. His eldest son, Christian, lives in Washington, D.C. His youngest son, Giancarlo, attends Purdue University. Antunes splits his time primarily between the Washington, D.C. and Sintra, Portugal.