Justin Trudeau three half-siblings, Kyle and Alicia, from his mother's remarriage to Fried Kemper, and Sarah, from his father's relationship with Deborah Coyne. Trudeau lived at 24 Sussex Drive, Ottawa, the official residence of Canada's prime minister, from his birth until his father's government was defeated in the federal election on May 22, 1979. The Trudeaus were expected to move into the residence of the Leader of the Official Opposition, Stornoway, at 541 Acacia Avenue in Rockcliffe Park, but because of flooding in the basement, prime minister Joe Clark offered them Harrington Lake, the prime minister's official country retreat in Gatineau Park,
Harrington Lake property at Harrington Lake has been managed by the National Capital Commission. The property includes four recreational buildings; the land, which formerly consisted of cultivated fields, has reverted to secondary forest. In addition to the main cottage with its fine view over the lake, the Harrington estate includes the following structures: The lake itself and the area around it are referred to as "Lac Mousseau". The name "Harrington" is thought to be a misspelling of "Hetherington", the name of a family which settled in this area. The French name "Mousseau" comes from another early settler to the area, Louis Mousseau,