Editor's Note: (Michael D'Antonio is the author of the book "Never Enough: Donald Trump and the Pursuit of Success" and co-author with Peter Eisner of "The Shadow President: The Truth About Mike Pence." The opinions expressed in this commentary are his own. View more opinion on CNN.)
(CNN) Born into a fabulously wealthy family of seemingly continuous intrigues, betrayals and conflicts, Mary L. Trump did not seek the spotlight. She earned a master's in literature at Columbia and a doctorate in psychology at Adelphi University.
These disciplines seem to have prepared her to understand and reveal deep truths in a way that would make the family's secret-keepers freak out. It's safe to assume they are freaking out now.
In late July Dr. Trump will publish a book, ominously titled, "Too Much and Never Enough: How My Family Created the World's Most Dangerous Man."
Most readers won't need any more clues about her subject -- her uncle, President Trump. But those who do could consult the cover, which features a photo of a young Trump before he became the figure who now lumbers upon the world stage and lurks in so many nightmares.
Three and a half years into the Trump era, endless words have been spent illustrating the chaotic and cruel personality that can, to cite just one example, schedule a huge ego-gratifying rally in the middle of a deadly pandemic caused by a viciously contagious virus.
According to her publisher, Mary Trump will bring her special perspective -- insider, psychologist, writer -- to bear on incidents and information never before revealed.
Having devoted years to the study of the man and the Trump clan, I can say that the bits teased so far suggest that Mary Trump has the goods. To begin with, she's the daughter of the President's eldest sibling, Fred Trump Jr., who may have been the original victim of Donald Trump's bullying.
As publisher Simon and Schuster put it: "She recounts in unsparing detail everything from her uncle Donald's place in the family spotlight and Ivana's penchant for regifting to her grandmother's frequent injuries and illnesses and the appalling way Donald, Fred Trump's favorite son, dismissed and derided him when he began to succumb to Alzheimer's."
Warm and easygoing, Fred was, by all accounts, ill-suited to play the role of cutthroat real estate baron, which was what his father expected of him. Happy to step in, Donald did all he could to prove that he was the more deserving son.
When Fred Jr. finally ceded first position among the heirs to the family business, he became an airline pilot. Donald mocked his profession. "What's the difference between what you do," he would ask, "and driving a bus?"
After Fred Jr. died at age 42 from complications of alcoholism, Donald turned his death into an object lesson that reflected well on himself. Donald pointedly abstained from tobacco and alcohol because of his brother's struggle, saying, "I watched him. And I learned from him."
The cruelty didn't stop with Fred Jr.'s death in 1981. Later, when the paterfamilias Fred Trump Sr. died, heirs learned that his will distributed his estate among his children and their offspring "other than my son Fred C. Trump Jr." The children of Fred Jr. sued, noting that an earlier will, written prior to Fred Sr. being diagnosed with dementia, had granted them proper shares.
Soon after the suit was filed, Donald changed a health insurance policy, taking away coverage for a disabled infant born to Fred's own son, Fred III. (A second telling anecdote from author Harry Hurt III, who has written about the Trumps, describes Donald briefly considering evicting his brother and sisters from their rent-free homes in a Trump building unless they paid cash for the property.)
When asked in 2000 whether withdrawing the child's insurance was cold-hearted, the man who claimed to be a billionaire said, "I can't help that. It's cold when someone sues my father."
The suit was settled and the baby was again insured, but 16 years later, when he was running for president, Donald Trump seemingly had no regrets. Asked about the incident, he said, "I was angry because they sued."
For those who know the family lore, the circle is completed by a little anecdote published in Hurt's 1993 book "Lost Tycoon." Hurt reports overhearing Fred Trump Sr. talking about his son Donald and his wife Mary flying off together. "I hope their plane crashes," said Fred, adding that then "all my problems will be solved."
Reports on the upcoming book suggest that the author will share juicy stories she learned from the President's sister, Maryanne Barry. It wouldn't be the first time that Barry, perhaps inadvertently, revealed something true about her brother. Speaking with writer Gwenda Blair in 1990, Barry shared a story about when Donald was a young man and turned a game of catch with Barry's seven year-old son into a cruel contest.
"Donald kept throwing it faster and faster, harder and harder, until I hear this crack and the ball hit David's head. Donald had to beat the seven year-old."
This cold-hearted nature followed him into his political career. As president, Donald Trump has treated the children of asylum-seeking immigrants with great cruelty, separating them from their parents and locking them in cages. During our current pandemic, with over 116,000 dead in the US and more succumbing every hour, he has been so cavalier as to advocate dangerous unproven cures.
In my own experience as a Trump biographer I have answered questions about the origins of the President's weird ways by citing both genetics and his upbringing. This nature-and-nurture answer is a bit of a cop-out, but it is the best I have been able to muster after studying the man and his family.
Because she has lived close to the source and possesses real expertise in mental health, Mary Trump's opinion matters greatly to those seeking answers. I can't wait to read her book.