Síle de Valera Dublin, where she qualified as a career guidance teacher. De Valera comes from a famous political family; she is the granddaughter of Éamon de Valera, the founder of Fianna Fáil, former Taoiseach and third President of Ireland. She is a niece of the former TD Vivion de Valera and is a first cousin of Teachta Dála Éamon Ó Cuív. De Valera was first returned to Dáil Éireann in the Fianna Fáil landslide victory at the 1977 general election. She was elected for the Dublin County Mid constituency, which included the Tallaght area of County Dublin, being the youngest TD elected
Éamon de Valera and Collins would later become opponents during the Irish Civil War. In January 1921, in his first appearance in the Dáil, after his return to a country gripped by the War of Independence, de Valera introduced a motion calling on the IRA to desist from ambushes and other tactics that were allowing the British to successfully portray it as a terrorist group, and to take on the British forces with conventional military methods. This they strongly opposed, and de Valera relented, issuing a statement expressing support for the IRA, and claimed it was fully under the control of the Dáil.