Margaret Joan Trudeau (née Sinclair; born September 10, 1948) is a Canadian activist and the mother of Justin Trudeau, the 23rd prime minister of Canada. She married Pierre Trudeau, the 15th prime minister of Canada, in 1971, three years after he became prime minister. They divorced in 1984, during his final months in office. She is also the mother of the journalist and author Alexandre "Sacha" Trudeau, and Michel Trudeau (now deceased) with Trudeau, and of son Kyle (born 1984), and daughter Alicia (born 1988), with Ottawa real-estate developer Fried Kemper. She is the first woman in Canadian history to have been both the wife and the mother of prime ministers. Trudeau is an advocate for people with bipolar disorder, with which she has been diagnosed.

Trudeau was born in North Vancouver, British Columbia, Canada, the daughter of Scottish-born James "Jimmy" Sinclair, a former Liberal member of the Parliament of Canada and Minister of Fisheries and Oceans, and Doris Kathleen (née Bernard) Sinclair. Her grandmother, Rose Edith (née Ivens) Bernard, with whom she had an especially close relationship, lived in Roberts Creek, British Columbia, in later life, and was from Virden, Manitoba. Her grandfather, Thomas Kirkpatrick Bernard, was born in Makassar, Dutch Celebes, now in Sulawesi, Indonesia, and immigrated in 1906 at age 15 with his family to Penticton, British Columbia, eventually working as a payroll clerk for Canadian Pacific Railway.

The Bernards were the descendants of colonists in the Straits Settlements, the Dutch East Indies, and British Malaya, nowadays respectively Singapore, Indonesia, and Malaysia, including Francis James Bernard, a London, England-born Anglo-Irishman whose great-grandfather, Arthur Bernard, was a member of the Irish House of Commons for Bandonbridge, and brother of Francis Bernard, Solicitor-General for Ireland, and ancestor of the Earls of Bandon. Francis James Bernard was the founder of the Singapore Police Force in 1819, The Singapore Chronicle, the first newspaper in Singapore, was established with Bernard as owner, publisher, and editor in 1824 and he opened up Katong, now a densely populated-residential enclave, the first to cultivate a coconut estate there in 1823. In 1818, Bernard married Margaret Trudeau's 3rd great-grandmother, Esther Farquhar. She was the eldest daughter of Scotsman William Farquhar, a colonial leader in the founding of modern Singapore, by Farquhar's first wife, Antoinette "Nonio" Clement, who was the daughter of a French father and an ethnic Malaccan mother.

Another great-grandmother, Cornelia Louisa Intveld, married in 1822 to Royal Navy officer and merchant, William Purvis, from Dalgety Bay, Scotland, and a first cousin of American abolitionist Robert Purvis; she was a noted fine soprano and a beauty of her era. Upon glimpsing her across the auditorium at the opera in London, England, British King William IV sent his equerry to invite her to his box. After she refused, the King sent the equerry back just to ask her name. Intveld was born in Padang, present-day West Sumatra, Indonesia. At the time of Intveld's birth, Padang was in the territory of the Pagaruyung Kingdom, where her father, who came from humble beginnings in Hellevoetsluis, South Holland, rose up through the Dutch East India Company to become the Dutch Resident of Padang. Her maternal grandmother was an Ono Niha ranee (a term covering every rank from chieftain's daughter to princess) who married a prominent Dutch colonial official and merchant. Acclaimed British harpsichordist Violet Gordon-Woodhouse, and Hawaiian settler Edward William Purvis who, according to popular belief, was the namesake of the ukulele, are Margaret Trudeau's first cousins, three times removed. Trudeau explored her mother's family's roots in Singapore during an episode of Who Do You Think You Are?

Trudeau's family moved to a large house in Rockcliffe Park, Ontario, in 1952 after her father was appointed to the Cabinet, and she attended Rockcliffe Park Public School although they returned to North Vancouver after he lost his re-election bid in 1958. She attended Hamilton Junior Secondary School and Delbrook Senior Secondary School in North Vancouver. Trudeau graduated in 1969 from Simon Fraser University in Burnaby, British Columbia with a Bachelor of Arts in sociology.^{[better source needed]}

Sinclair met Pierre Trudeau, who was then Minister of Justice, while vacationing in Tahiti with her family when she was 18. Sinclair did not recognize him, and she in fact thought little of their encounter, but Trudeau, then 47, was captivated by the carefree "flower child" and began to pursue her.^{[citation needed]}

Pierre Trudeau was a bachelor before he became Prime Minister in 1968. They kept their romance private, so Canadians were shocked after the Canadian Broadcasting Corporation led its morning radio broadcast about Prime Minister Trudeau honeymooning at Alta Lake, British Columbia, at the foot of Whistler Blackcomb Ski Resort the day after a surprise wedding in North Vancouver, British Columbia, on March 4, 1971. Although she had accompanied Pierre Trudeau in public a year before to ice skate and dance at an event at Rideau Hall, official residence of Canada's Governor General, it was a complete secret except to immediate family members and close friends that she was in a romantic relationship, then in a six-month engagement to the Prime Minister.

As Pierre Trudeau was a Catholic, she converted to the Catholic Church for their marriage. When asked about her role in a marriage to the prime minister, Trudeau said, "I want to be more than a rose in my husband's lapel."^{[citation needed]}