Have you recovered from Royal Baby Magic? It's been a little over a week since Prince Harry and Meghan Markle announced her pregnancy to the entire world, and the entire world promptly freaked out. It felt like it had been a long time coming while simultaneously being a total freakin' surprise. The two lovebirds have only been married since May, but my body was fully ready for a new royal baby, and here they are!
The royal baby isn't even due until the spring, and yet we already have a clue or two about what their last name won't be: Cambridge. You're probably wondering why they have a different last name than that of their cousins, Charlotte, George, and Louis. That's a good question! Since Harry and Meghan were gifted the title of the Duke and Duchess of Sussex by the Queen on the morning of their wedding day, that's why their future child's name will be Sussex. George, Charlotte, and Louis are the offspring of the Duke and Duchess of Cambridge, thus why their last name differs.
Considering that the royals typically forgo the whole "last name" business, they're still required to have one when they begin attending school and for official government papers. After all, it'd be weird to have a child whose first name is "His Royal Highness," but maybe that's just me.
For example, Harry and William went as Harry Wales and William Wales during their education, mostly due to their father's title as the Prince of Wales. In April, when Prince Louis was born, his surname was listed as "His Royal Highness Prince Louis Arthur Charles of Cambridge."
However, they may have an alternative opportunity for a surname that Harry & Meghan may want to use, and fans of The Queen may recall the moment when Her Highness, in 1917, made the decision to incorporate Prince Phillip's last name to her own to take on the surname of Mountbatten-Windsor. Any descendants of the Queen born after 1960, other than those with a royal title, has the last name Mountbatten-Windsor.
But then again, Harry and Meghan might change their minds and pick their own last name! We never know with these crazy kids.