In this revelatory, authoritative portrait of Donald J. Trump and the toxic family that made him, Mary L. Trump, a trained clinical psychologist and Donald's only niece, shines a bright light on the dark history of their family in order to explain how her uncle became the man who now threatens the world's health, economic security and social fabric.

Mary Trump spent much of her childhood in her grandparents' large, imposing house in New York, where Donald and his four siblings grew up. S ...