2008: For her 26th, she and little sister Pippa headed to da club (in pantyhose and a pea coat).
Receiving the card, William hilariously added that he was too, off the hook, because he remembered it was Kate's birthday that morning.
Some royal fans believe that Kate and William will want to have four children, just as William's grandmother Queen Elizabeth II has four children (Prince Charles, Prince Edward, Princess Anne and Prince Andrew).
But since becoming a mother, the Duchess has preferred to celebrate privately with her close family.
2012: Her first birthday as a royal (AND ALSO HER 30th), Middleton pre-gamed at the London premiere of War Horse the night prior, and celebrated her big day with friends and family with a dinner in Kensington Palace's private dining room.
Commoners across the United Kingdom have turned their attention away from Brexit and a looming general election to monitor changes to English royal Kate Middleton and her ambiguous baby bump.
2015: Pregnant (again), Kate spent another quiet birthday at home.
2017: Again, Middleton celebrated 35 outside of the spotlight at her Norfolk home. Talking about his son's fondness for dancing, Prince William previously said: "George is doing dancing as well, he loves it".
Mother-of-three Kate is thought to have enjoyed a birthday cake and been given presents.