The revelation is contained in Justin Trudeau's first memoir, titled Common Ground, which is published by HarperCollins Canada and will be publicly released on Monday.
His dad, whom he called "Papa" because he spoke French to him, served as Canada's prime minister for 15 years. But Pierre's marriage to Margaret crumbled by the time Justin was 13.
Trudeau shared his dad's counsel with his wife Sophie in the spring of 2012, when he started to seriously consider a run at the Liberal leadership.
"I recalled for Sophie that my father had once told me I should never feel compelled to run for office. 'Our family has done enough,'" Trudeau says his father told him.
The once mighty Liberal Party of Canada had suffered a devastating blow following the 2011 federal election, being reduced to the worst showing in the party's history.
Trudeau's biography, at age 42, comes 12 months ahead of next year's election, which is scheduled for Oct. 19, 2015. Like Barack Obama, Hillary Clinton and other leaders before him, the memoir is Trudeau's attempt at defining himself before his political opponents do it for him.
The book recounts several key moments of Trudeau's young life including:- The collapse of his parents' marriage which he hesitated to address at first but which he recalls as "a succession of painful emotional snapshots."
- His mother Margaret's deteriorating mental health and the responsibility he felt to help her.
- What he came to appreciate as the "widening difference" in personality between him and his brother Sacha.
- The death of his youngest brother Michel who was killed in an avalanche while skiing in B.C. and the death of his dad two years later.
- His relationship with Sophie Grégoire. He describes their marriage as "not perfect," but says she "grounds" him.
- His charity boxing match with suspended Senator Patrick Brazeau, otherwise known as the "Thrilla on the Hilla." Trudeau describes his win as the "first clear victory for Liberals" following the blow Canadians dealt the party during the 2011 election.
A Liberal-NDP coalition?
His leadership campaign began in earnest around a campfire in Mont-Tremblant, Que., in the summer of 2012.
Trudeau writes it was there that he debated the future of the party with a group of his most trusted friends. No topic was off-limits.
"Should the Liberal Party continue to exist? Should we join forces with the NDP to form a united alternative to the Conservatives? Or maybe we ought to form a new political party entirely," Trudeau asked his friends, he writes.
"I'm sure it will alarm some partisan Liberals to read this, but the debate was serious."
"We took the merger option out for a much longer test drive," Trudeau writes.
While good arguments were made on both sides, Trudeau said differences of opinion with the New Democrats were "too profound" for him to ever support a merger.
For instance, he could never support the NDP's policy to repeal the Clarity Act, a law born following the 1995 Quebec referendum. "This was a non-starter for me."
The idea of merging with the NDP was laid to rest.
While he would not formally announce his campaign until a couple of months later, at the end of those three days, Trudeau said he and Sophie decided he would take the plunge into leadership politics.
Trudeau and his team agreed to focus on reforming the party from the grassroots up.
Harper's 'rabid form of partisanship'
His dad's advice not to feel obligated to jump into politics came, Trudeau said, "despite having never experienced the incessant, base vitriol of 21st century politics."
While Trudeau has repeatedly vowed not to engage in personal or negative attacks against his political opponents, in his memoir he doesn't shy away from chiding Stephen Harper's Conservatives for what he sees as their petty and hyperpartisan style of politics.
"One of the Harper years' most pernicious developments is a rabid form of partisanship, the idea that politics is warfare and political adversaries are to be treated as enemy combatants," he writes.
Trudeau deplores the Conservative government's dismissal of the middle class, their approach to climate change, their view of immigration, their lack of vision around infrastructure, as well their "reckless attacks" on Canada's public institutions.
He even goes as far as to say the Conservatives are ignoring the West.
"All these deficiencies spring from a common root cause: the autocratic, 'my way or the highway' spirit that has taken hold inside the current Conservative Party."
New Democrats get 'the big things wrong'
The Liberal Party's fight for the centre is nowhere more apparent than in Trudeau's criticism of the NDP.
Trudeau writes that he respects the NDP's history but criticizes the Opposition New Democrats for "getting the big things wrong."
And although he does not refer to the NDP leader by name, Trudeau dismisses fellow Quebecer Tom Mulcair's stance on resource development.
Mulcair had told CBC Radio's The House in May of 2012 the resource sector in western Canada was artificially driving up the dollar, making it tough on eastern manufacturers and exporters.
"It serves nobody to suggest that western Canada's resource wealth is a 'Dutch disease' that weighs down the rest of the economy. My party learned that painful lesson under my father's leadership," Trudeau writes.
Trudeau does concede that the so-called 2011 Orange Wave under the late Jack Layton did not happen overnight but "was years in the making."
Yet he appears to take a harsher tone with the New Democrats, starting with the leadership race that saw Mulcair elected as leader.
"If you want to replace a government, you have to provide a choice, not an echo. As I watched their convention unfold... It seemed to me they had decided the only way to defeat the Conservatives was to create a mirror image, only on the left."
Trudeau concludes the book with a final pitch to Canadians:
"I want to be Canada's prime minister because I think I have a better idea of this country — and better ideas for this country — than my political opponents do."
While Trudeau continues to be criticized for a perceived lack of substance, the Liberal leader has said he will not release his party's platform before the writ is dropped in 2015.
He is donating all proceeds of the book to the Canadian Red Cross Society.