Mary Margaret (Hehir) O'Mahony of Ireland was born in March 1892 to Michael T Hehir and Marguerita (Quinn) Hehir. She has siblings James Christopher "Jim" Hehir, Michael Joseph Hehir, Eileen "Eily" (Hehir) Bryant, Esther Marie Hehir, and Anna Gertrude Hehir- Cannon. Mary O'Mahony married Thomas F. 'Tomás' O'Mahony in April 1920 in Portsmouth, Portsmouth County, England United Kingdom, and has children Micheál J. 'Hauley' O'Mahony, Margaret (Peggy) O'Mahony (Mahony), Mary (O'Mahony) (Mahony), Monica 'Mona' (O'Mahony) Maloney, Eileen (O'Mahony), Evelyn (O'Mahony) Quinn, and Joan O'Mahony.