Mary Trump revealed the truth about her uncle in a bookMary Trump probably deserves a lifetime achievement award for turning into the ultimate whistleblower on Trump. The clinical psychologist didn’t just write one scathing exposé about her uncle Donald—she penned multiple bestsellers dissecting the Trump family dysfunction with an eye for detail. But Mary’s contributions weren’t only to psychologically deconstruct the web of egotism defining the Trump family. Meet Maryanne Trump, the sister who spilled everything on tapeDonald Trump has an older sister, a retired federal judge named Maryanne Trump Barry. George regularly lambasted Trump on social media, called him mentally unfit, and Trump responded by dubbing him “Mr.