Christie Brinkley opened up about her estranged brother, Greg Brinkley, during a conversation about her new memoir 'Uptown Girl' at the 92nd Street Y in New York City. The model and author shares why her sibling wasn't included in the book.

Brinkley writes in her memoir that it started out as a song for a "mystery girl" Joel had been having phone conversations with, but when his relationship with Brinkley began, he finished it in her honor. Their relationship was then immortalized in the hit song's iconic music video, in which Brinkley appears in.