Here are 10 things you probably didn't know:
— When youngest brother Michel was swept by an avalanche into B.C.'s Kokanee Lake in 1998, his death had a profound impact on the family, especially Trudeau's father, former prime minister Pierre Trudeau. A lifelong devout Catholic, Pierre "seemed angry with God;" his faith was weakened, as well as his physical constitution.
"The lights began to dim in my father's soul when Michel died," Justin writes of his father, who died two years later.
By contrast, Justin, a "lapsed Catholic" at the time, says the tragedy caused him to "welcome God's presence into my life" and to "reaffirm the core of the Christian beliefs I retain to this day."
— When Pierre was diagnosed with prostate cancer and chose not to pursue treatment, he did not tell his eldest son. Justin, who was teaching at a school in Vancouver at the time, was told only when it appeared the disease had entered its terminal phase.
It had been "Dad's orders to keep me in the dark," Trudeau writes. "My father knew I would drop everything I was doing in Vancouver and return to Montreal the moment I heard about his condition. He didn't want me to quit on my students before the school year was over."
— Trudeau's mother, Margaret, enrolled him in ballet classes when he was six years old. She gave up on the classes after literally having to drag him kicking and screaming out the door and being admonished by a workman at 24 Sussex to "give the kid a break."
— At their "austere" art deco home in Montreal, Pierre had a floor that was "strictly off limits to all but him," housing his bedroom, his study, a library and a hallway lined with mementoes and photos from world leaders.
Pierre imposed rules about the language to be spoken on each floor. The top floor, which included the kitchen and living room, was strictly French. He would reprimand Justin and his friends if he heard them speaking English on that floor.
The three brothers had their own floor where they engaged in much play-fighting, including judo and wielding sticks and swords.
"There were few rules, other than no punches in the face and no biting, and if someone got hurt, we stopped."
— The play fights sometimes became real. On one occasion, when Justin was driving his brothers to their mother's cottage, "for some bizarre reason, we got into a raging argument about who would control the car windows."
"It got so heated that I pulled over to the side of the road and we all piled out of the car to have a real, not play, fight. Michel and Sacha teamed up to pin me to the ground."
When their father heard about it, "he read us the riot act. 'No matter what happens, the three of you need to stick together,' he told us."
— Trudeau has had little contact with his half-sister, Sarah Coyne. He saw her a few times as a baby, a few more when she was a toddler and he took delight in seeing his father, "approaching 80, carrying Sarah around on his shoulders." Justin went rock climbing with Sarah a few days before his father's death in 2000.
"After the funeral, with Dad gone, we lost touch. I remain proud of my half-sister and look forward to connecting again in the future."
— For all his advocacy for the legalization of marijuana and his admission to having smoked joints a half dozen times, including once after becoming an MP, Trudeau drinks little and learned to be wary of both drugs and alcohol while working as a bouncer at a B.C. night club.
"Being dependent on drugs and alcohol for your happiness is a trap that has ruined too many lives and I resolved long ago that it wouldn't ruin mine."
— Trudeau was so happily off-balance during his first date with wife Sophie Gregoire that he "actually walked into a lamp post." He proposed to her that same night.
"I'm 31-years-old, so I've been waiting for you for 31 years," he told her. "Can we just skip the boyfriend/girlfriend part and go straight to engaged since we're going to spend the rest of our lives together?"
— Before he made the final decision to toss his hat into the Liberal leadership ring in, Trudeau and his inner circle seriously discussed whether the Liberal party ought to continue to exist or merge with the NDP to ensure defeat of the Conservatives.
"We owed it to ourselves and to our country to ask the questions directly and seriously," he writes. "Was the Liberal party in the way? Did our continued existence perpetuate Conservative rule and therefore imperil much of what our party had fought for over the years?"
Trudeau ultimately decided his disagreement with New Democrats over "critically important, substantive matters," such as the rules for negotiating the secession of Quebec, were too profound for a merger to work.
— Trudeau admires the way Preston Manning created the Reform Party, precursor to today's Conservative party, around the rallying cry, "the West wants in," in the aftermath of exclusionary policies such as his own father's reviled national energy program.
"In the entrepreneurial fashion that has come to rightly typify the West, the local response to a political movement that excluded them was to create one that couldn't live without them, and to build that movement until it governed the whole country. When you take a step back and think about it, it was an awesome achievement, maybe unparalleled in our political history."
He believes, however, that Prime Minister Stephen Harper, one of the original Reform MPs, has "forgotten this basic element of the Conservative party's success."
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