Donald Trump's only niece Mary has written a book about the toxic family history that she believes shaped her uncle.
She talks to Kathryn Ryan about the revelations contained in Too Much and Never Enough: How My Family Created the World's Most Dangerous Man.
Mary says she never thought her uncle would win the Republican Party nomination, let alone the presidential election.
"I laboured under the delusion that, as bad as he would be if he got into the Oval Office, I thought there were enough safeguards in place to keep him from doing the kinds of damage and amount of damage he's done. Clearly I was wrong. He has so many enablers within the Republican Party. It's been a bigger disaster than even I would have imagined."
She says she wouldn't have written a book about her family if it wasn't for her fear about what is happening to the United States under her uncle's leadership.
She sees a connection between his behaviour within their family and his behaviour as president.
It all leads back to Fred Trump Senior, Donald and Freddy's father and Mary's grandfather, who she describes as a "high-functioning sociopath".
Fred and his wife Mary Anne had five children – Maryanne, Freddy, Elizabeth, Donald and Robert, who died recently.
Mary's father Freddy, Donald's older brother, had a lot going for him as a younger man but died an alcoholic at 42.
Mary believes Fred Trump Senior disliked and disrespected his second son from the time Freddy was a teenager.
Donald, on the other hand, had the kind of personality that resonated with his grandfather.
"[Donald] was obnoxious, he never admitted his mistakes, he never apologised for anything. And he knew my grandfather needed a son that was the tough guy and the killer.
"Donald knew that there could be only one winner in the family … there could be only one person to get any kind of positive attention at all, and that included money and approval."
Donald was unkind to Freddy, Mary says.
"Donald knew, on some level, that it was only by a stroke of luck that he became my grandfather's favourite. Because he had seen my dad grow up to be successful, be loved by his friends, be skilful … He, like my grandfather, felt the need to humiliate [Freddy], no matter how badly my dad was doing.
"If Donald had an opportunity to be kind he wouldn't be because my grandfather would disapprove … and think less of Donald, and that was not going to happen."
When her father died in 1981, Mary was 16 and she felt a lot of guilt about not doing enough for him.
To this day, she is still ashamed of buying into the "myth" that her father was an "alcoholic loser" undeserving of respect.
Mary has not spoken to her aunt Maryanne since she released secretly made audio recordings of Maryanne speaking against Donald earlier this month.
"I knew that the Republican convention, which took place last week, was going to be a lie from beginning to end and that one of the lies told would be that Donald was a great family man who had empathy for other people.
"Clearly that is not what one comes across in the tapes. His own sister, who has known him his entire life, says he's cruel, he has no loyalty and he can't be trusted. That's something that the American people need to hear and need to believe and need to understand so that they don't make the same horrible mistake that they did in 2016."
Donald Trump has an ability to speak to people's worst instincts, which is easy to do when you keep them in a state of fear and suspicion, Mary says.
"We have plenty of reasons now to be afraid. The pandemic, which is ravaging our country almost entirely due to Donald's malpractice and inaction, we are on the brink of economic collapse for the same reason and social strife is running rampant in this country – not because of Donald's inaction but because he's encouraging it."