Duchess Kate got to catch up with one of her favorite celebrities, Sir David Attenborough, and introduce him to one of his youngest fans — her eldest son, Prince George.Kate, 38, and her husband, Prince William, 38, and their kids, George, 6, Princess Charlotte, 5, and Prince Louis, 2, caught up with the British broadcaster and naturalist in the garden of Kensington Palace in London, as seen in new pics released by the palace on Saturday, September 26.“The Duke and Duchess of Cambridge are