Mary Lou McDonald was born in Dublin on May 1, 1969 and is the new president of Sinn Fein. Her father, Patrick, was a very successful surveyor, married to Joan. She has two brothers: Bernard, a scientist and Patrick, a patent lawyer. Her sister, Joanne, is a teacher. She was educated at Trinity College, Dublin, the University of Limerick and Dublin City University, studying English Literature, European Integration Studies and Human Resource management.
After leaving university, the politician ran for the leadership unopposed and had served as deputy leader since February 2008. She has been a Member of Dáil Éireann, the equivalent of an MP, for Dublin Central since 2011 and had previously served as an MEP for the Dublin constituency from 2004 to 2009.