Editor’s Note: Michael D’Antonio is the author of the book “Never Enough: Donald Trump and the Pursuit of Success.” His forthcoming book, “The Hunting of Hillary: The Forty Year Campaign to Destroy Hillary Clinton” is out later this month. The opinions expressed in this commentary are his own. View more opinion on CNN.

CNN  — 

No one will ever fully explain Donald Trump: the cruelty, the vanity, the insecurity converted to massive overconfidence. However, in “Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man,” his niece Mary L. Trump comes closer than anyone to describing the making of a seemingly heartless person who won his way to the White House.

Michael D'Antonio

On page after page of this book, to be published next Tuesday, the author relies on her perspective as an insider and her expertise as a psychologist to reveal the family dynamic that produced a person capable of the kind of outrageous acts Trump has committed. This is, after all, a man who used insult, racism, and lies to gain and maintain power. A president whose leadership contributed to lethal fiascos involving asylum-seeking children, hurricane victims and, now, a pandemic made far worse by his bungling. Through it, he has seemed immune to feelings of regret, grief and empathy.

The President’s brother unsuccessfully sought to block publication of the book, alleging that a legal agreement made to settle a dispute prohibited it. At the time, Robert Trump, calling his niece’s actions “a disgrace” said, “Her attempt to sensationalize and mischaracterize our family relationship after all of these years for her own financial gain is both a travesty and injustice to the memory of my late brother, Fred, and our beloved parents.”

Whatever the elder Trumps may feel, Mary Trump marshals enough memories and family lore to make a plausible case for her assessment of the president and his clan. I did not speak with her when I was researching the biography I wrote about Trump, but I find her account persuasive. Her description of her grandfather aligns with what others told me about his cold and demanding nature. Likewise, her description of how Fred Sr. backstopped Donald Trump during years when his son made a series of bad business decisions rings true to the public record and what many sources told me. All in all, it strikes me as an accurate report.

On a personal scale Mary Trump saw precedent for Donald Trump’s coldness in how her uncle treated her own father as he was dying. Donald Trump has always spoken of Fred Trump Jr., his older brother, as a man felled by addiction to alcohol. This is true. Mary Trump also alleges that Fred Jr. was mistreated by his father, whom Mary regards as a “high-functioning sociopath” and by Donald Trump, who was a chip off the old block. Together they made Fred Jr. miserable, she writes.

Trump pushed him aside to become heir apparent to the family business and Fred was marginalized, she says. All of this was consistent with the head of the family’s value system. In Mary Trump’s telling, the older Trump regarded human softness as shameful and weakness as unacceptable. He taught his sons “be tough at all costs, lying is okay, admitting you’re wrong or apologizing is weakness.” In life “there can only be one winner,” Fred Trump used to say, according to her account, “and everybody else is a loser.” This attitude may explain the author’s claim that as Fred Jr. lay dying of a cardiac condition the family waited a week before seeking medical help.

Decades later, Mary Trump says she sees the dysfunction she witnessed as a young member of the Trump clan playing out on a national scale during the pandemic. Instead of acting swiftly to address Covid-19, the President has refused to take responsibility for early mistakes or to meaningfully adjust as things grew worse. Incapable of facing even a hint of failure, he has offered distractions and denials until he has seemed to lose interest. Recently the Washington Post reported that the White House may be hoping people just get used to the illness and death.

“While thousands of Americans die alone, Donald touts stock market gains,” Mary Trump writes. “As my father lay dying alone, Donald went to the movies. If he can in any way profit from your death, he’ll facilitate it, and then he’ll ignore the fact that you died. … The fact is that Donald is fundamentally incapable of acknowledging the suffering of others. Telling the stories of those we’ve lost would bore him.”

In one of the most famous episodes of the Trump family story, Mary Trump and her brother sued after discovering that as their father’s heirs they were denied a share of Fred Sr.’s estate

The suit was eventually settled out of court but the hard feelings that were stirred did not disappear. Mary Trump wrote that she got a reminder of where her father stood with the family when, after her grandmother died, he wasn’t mentioned as one of her children in the published obituary.

In writing and publishing her book now, decades after the will dispute was settled, Mary Trump has opened herself up to the possibility that she will be subject to more vilification by the President and his allies. Kellyanne Conway, the President’s counselor, has already taken a few swipes at her, noting that books are “not fact checked, nobody’s under oath.” She also warned against “a rush to slap credibility on whoever’s getting the President that day.”

In fact, Mary Trump has ample credibility, due to a life spent dealing with the extended Trump clan, including her powerful uncle. This credibility is amplified by her professional qualifications and by the mix of fierce honesty and decency she appears to display throughout the book as she reveals the good and the bad. Her decency can be seen in the compassion she shows for the Donald Trump who, as a very little boy, she writes, was deprived of a mother’s care, due to her many illnesses and whose father was incapable of offering loving attention. “Donald’s main source of comfort and human connection was taken from him,” she writes. Left to the care of household staff and a disinterested father, she adds, “Donald suffered deprivations that would scar him for life.”

One suggestion of the way that Donald Trump’s development was arrested in childhood comes in an anecdote that Mary Trump shares of an incident that occurred from inside the White House. Invited to a family celebration after the election, she catches the sound of a familiar story about one of young Donald’s brothers dumping a bowl of mashed potatoes on the future President’s head. She looks to see if the older Trump is finally able to laugh at himself. Instead, she recalls, he folded his arms on his chest and glowered.

Get our free weekly newsletter

  • Sign up for CNN Opinion’s newsletter.
  • Join us on Twitter and Facebook

    In the same part of the book, Mary Trump notes that the President’s older sister Maryanne Barry, a former federal appellate court judge, considered him a “clown” with “no principles.” The author also describes how when her uncle was campaigning for president, she heard echoes of Trump family dinners in the way that candidate Trump mocked and disparaged others. “That kind of casual dehumanization of people was commonplace at the Trump dinner table,” she writes.

    Mary Trump resists giving the President a formal diagnosis. However, she does note his narcissism and suggests that he seems to fit many of the criteria for the serious diagnosis of anti-social personality disorder. “He is and always will be a terrified little boy,” she says. It is her concern over the damage a terrified person might do, she writes, that makes her call him “the world’s most dangerous man” and compelled her to tell the truth she knows. The result is an insightful, well-crafted memoir written by someone familiar with the Trump story from the inside and out – and who wrote it in spite of family pressure to stop her.