Shafaq news/ In a new book, a niece of US President, Donald Trump, applies her training in psychology to conclude that the president likely suffers from narcissism and other clinical disorders - and was boosted to success by a father who fueled those traits.

In "Too Much and Never Enough: How My Family Created the World's Most Dangerous Man," Mary Trump writes of a "malignantly dysfunctional family" dominated by a patriarch, Fred Trump, who showed little interest in his five children other than grooming an heir for his real-estate business.

Ultimately, he settled on Donald, she wrote, deciding that his second son's "arrogance and bullying" would come in handy at the office, and encouraged it.

He short-circuited Donald's ability to develop and experience the entire spectrum of human emotion", Trump writes, "Donald requires division. It is the only way he knows how to survive - my grandfather ensured that decades ago when he turned his children against each other".

The book, due out next Tuesday, is the first Trump biography written by a family member. Reuters obtained a copy of the book. The president's brother Robert has tried unsuccessfully, so far, to block its publication. The court battle continues but is not expected to halt publication.

White House press secretary Kayleigh McEnany said on Tuesday that it was a "book of falsehoods." Its publication comes as Trump, a Republican, seeks a second term in the Nov. 3 presidential election.

Mary Trump has a troubled history with her uncle, who clashed with her father, Fred Jr., before he died at age 42 after a battle with alcoholism.