However, there's one December 25th morning rule we can't get our heads around. According to the family's former chef of 15 years Darren McGrady, the royal women spend the first hours of Christmas Day in their own rooms - no Dukes allowed.
The women eat breakfast - including fruit, toast, and coffee - in bed, while the men head downstairs to the dining room to eat theirs.
That's right: Meghan's first Christmas morning as an official Duchess will be spent alone.
"The Queen’s tray is delivered at exactly 9 a.m," McGrady told Daily Mail.
"The male royals, meanwhile, come downstairs to the dining room for a hearty breakfast at 8.30 a.m. with eggs, bacon and mushrooms, kippers and grilled kidneys, to set them up for the 11 a.m. church service at St Mary Magdalene," he added.
Thankfully, Meghan and Kate are allowed to join Harry and William after breakfast: "When they return, it’s straight into pre-lunch drinks. This is where Meghan may find she can request a glass of her favourite wine, Tignanello, a full-bodied Tuscan red, McGrady said.
"The Queen has a gin and Dubonnet, while Prince Philip has beer. Everyone else will sip a glass of Veuve Clicquot and nibble on nuts. Canapes before a full Christmas lunch are rather frowned upon."