Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge sit in front of the Taj Mahal during day seven of the royal tour of India and Bhutan on April 16, 2016 in Agra, India Ian Vogler-Pool/Getty Images
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge, with their children, Princess Charlotte and Prince George, enjoy a short private skiing break on March 3, 2016 in the French Alps, France. ohn Stillwell - WPA Pool/Getty Images
Prince George of Cambridge is held by Prince William, Duke of Cambridge as Catherine, Duchess of Cambridge, Prince Harry and Queen Elizabeth II look out on the balcony of Buckingham Palace during the Trooping the Colour on June 13, 2015 in London, England. Chris Jackson/Getty Images
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge attend 'Rippa Rugby' in the Forstyth Barr Stadium on day 7 of a Royal Tour to New Zealand on April 13, 2014 in Dunedin, New Zealand. David Rowland - Pool/Getty Images
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge, depart The Lindo Wing with their newborn son at St Mary's Hospital on July 23, 2013 in London, England. Chris Jackson/Getty Images
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge pose wearing traditional island clothing during a visit to the Governor General's house as part of their Diamond Jubilee tour of the Far East on September 16, 2012 in Honiara, Guadalcanal Island. Chris Jackson/Getty Images
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge watch a rodeo demonstration at a Government Reception at the BMO Centre on July 7, 2011 in Calgary, Canada. The newly married Royal Couple are on the eighth day of their first joint overseas tour. Chris Jackson/Getty Images
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge look on during an an official welcome ceremony at the Somba K'e Civic Plaza on July 5, 2011 in Yellowknife, Canada. Chris Jackson/Getty Images
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge pose for the official tour portrait for their trip to Canada and California in the Garden's of Clarence House on June 3, 2011 in London. England. Chris Jackson / Getty Images for St James's Palace
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge make the journey by carriage procession to Buckingham Palace following their marriage at Westminster Abbey on April 29, 2011 in London, England. Julian Finney/Getty Images
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge drive from Buckingham Palace in a decorated sports car on April 29, 2011 in London, England. Jeff J Mitchell/Getty Images
Prince Harry (L) and Prince William (C) and Kate Middleton (R) cheer on the English team during the RBS Six Nations Championship match between England and Italy at Twickenham on February 10, 2007 in London, England. Richard Heathcote/Getty Images
The Duke and Duchess of Cambridge and the Prince during a visit to the Sensational Butterflies exhibition at the Natural History Museum, London. John Stillwell/PA Wire
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge pose with basketball player LeBron James (R) backstage as they attend the Cleveland Cavaliers vs. Brooklyn Nets game at Barclays Center on December 8, 2014 in the Brooklyn borough of New York City. Tim Rooke - Pool/Getty Images
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge leave St Paul's Cathedral after a Service of Commemoration for troops who were stationed in Afghanistan on March 13, 2015 in London, England. Chris Jackson/Getty Images
Prince William, Duke of Cambridge and Prince George of Cambridge arrive at the Lindo Wing after Catherine, Duchess of Cambridge gave birth to a baby girl at St Mary's Hospital on May 2, 2015 in London, England. Chris Jackson/Getty Images
Catherine, Duchess of Cambridge, Prince William, Duke of Cambridge, Princess Charlotte of Cambridge and Prince George of Cambridge arrive at the Church of St Mary Magdalene on the Sandringham Estate for the Christening of Princess Charlotte of Cambridge on July 5, 2015 in King's Lynn, England. Chris Jackson-WPA Pool/Getty Images
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge attend day nine of the Wimbledon Lawn Tennis Championships at the All England Lawn Tennis and Croquet Club on July 8, 2015 in London, England. an Walton/Getty Images
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge take a Game drive at Kaziranga National Park at Kaziranga National Park on April 13, 2016 in Guwahati, India. Heathcliff O'Malley - WPA Pool/Getty Images
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge prepare to leave on a safari in Kaziranga National Park on day 4 of the royal visit to India and Bhutan on April 13, 2016 in Kaziranga, India. Chris Jackson/Getty Images
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge, with their children, Princess Charlotte and Prince George, enjoy a short private skiing break on March 3, 2016 in the French Alps, France. John Stillwell - WPA Pool/Getty Images
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge are seen during their visit to the original Royal Research Ship Discovery as part of an away day to the Scottish City on October 23, 2015 in Dundee, Scotland. Danny Lawson - WPA Pool/Getty Images
The Duke and Duchess of Cambridge are on a three-week tour of Australia and New Zealand, the first official trip overseas with their son, Prince George of Cambridge. Mark Nolan/Getty Images
Prince William, Duke of Cambridge looks on as Catherine, Duchess of Cambridge fires an arrow during an Bhutanese archery demonstration on the first day of a two day visit to Bhutan on the 14th April 2016 in Paro, Bhutan. Chris Jackson/Getty Images
Britain's Catherine, Duchess of Cambridge (L), and Prince William, Duke of Cambridge feed baby elephants at the Centre for Wildlife Rehabilitation and Conservation (CWRC) at Panbari reserve forest in Kaziranga in the northeastern state of Assam on April 13, 2016. ADNAN ABIDI/AFP/Getty Images
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge walk down Kuniya Walk at the base of Uluru on April 22, 2014 in Ayers Rock, Australia. Scott Barbour/Getty Images
Catherine, Duchess of Cambridge holds Prince George of Cambridge as Prince William, Duke of Cambridge looks on whilst meeting a Bilby called George at Taronga Zoo on April 20, 2014 in Sydney, Australia. Chris Jackson/Getty Images
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge during a visit to Taronga Zoo on April 20, 2014 in Sydney, Australia. Chris Jackson/Getty Images
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge watch a bird display at Taronga Zoo on April 20, 2014 in Sydney, Australia. Chris Jackson/Getty Images
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge pose with Winmalee Girl Guides after planting a Summer Red Eucalyptus tree at Winmalee Guide Hall in Yellow Rock during the eleventh day of their official tour to New Zealand and Australia on April 17, 2014 in Winmalee, Australia. Anthony Devlin - Pool/Getty Images
Prince William, Duke of Cambridge, Catherine, Duchess of Cambridge and Prince George of Cambridge arrive at Sydney Airport on RAAF B737 on April 16, 2014 in Sydney, Australia. Ryan Pierse/Getty Images
Kate Middleton and Prince William on the day of their graduation ceremony at St Andrew's University in St Andrew's on June 23, 2005 in Scotland. Photo by the Middleton Family/Clarence House via GettyImages
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge leave The Lindo Wing of St Mary's Hospital with their newborn daughter on May 2, 2015 in London, England. Ian Gavan/Getty Images
