In honor of the Queen's 90th birthday, a bunch of royal family members sat down for interviews for a special documentary (airing March 27) that shares such fun and mundane facts as how the Queen liked to catch leaves as a child. One of the family members who chatted ever so politely about Queen Elizabeth II—whose big birthday is on April 21—was the Duchess of Cambridge. Speaking in a television interview for the first time by her herself, Duchess Kate had only nice things to say, because that's her job.