Kate Middleton , Prince William, Prince George, Princess Charlotte
Photo: Getty

Most families pass down a last name from one generation to the next, but the British royal family follows their own rules and traditions. They have formal titles that are made up of up to 15 words, but tend to only use Prince or Princess in front of their given name.

However, with the birth of Prince William and Kate Middleton‘s third child taking place any day now, many are curious as to whether he or she will adopt the surname the descendants of Prince Phillip and Queen Elizabeth often use on certain occasions: Mountbatten-Windsor.

Prince Phillip , Queen Elizabeth
Prince Phillip and Queen Elizabeth in 1947.
Photo: Getty

According to royal historian and writer of the Royal Musings blog Marlene Eilers Koenig, he or she will not. “The royal baby will not have a last name,” Koenig tells TownandCountrymag.com. “The name on the birth certificate will say HRH Prince or Princess, and all three names of Cambridge.”

HRH is an abbreviation for His or Her Royal Highness. The three names of Cambridge refers to the three first names given to each royal child. For instance, Prince George’s three first names are George Alexander Louis, and Princess Charlotte’s three first names are Charlotte Elizabeth Diana.

Kate Middleton , Prince William, Prince George, Princess Charlotte
Photo: Getty

“The House name is Windsor and the family name for those who do use a surname is Mountbatten-Windsor,” Koenig adds.

Mountbatten is Prince Phillip’s surname, and Queen Elizabeth II’s grandfather, King George V, took on Windsor—after Windsor Castle—as the British royal family’s official surname in 1917. According to the royal family’s website, George V initially belonged to the Saxe-Coburg-Gotha dynasty, but thought it sounded too German in light of Great Britain and Germany’s tensions during World War I.

Koenig also tells TownandCountrymag.com that Prince George, the royal baby’s oldest sibling, is listed at school with the surname Cambridge, which is part of his father and mother’s official titles as the Duke and Duchess of Cambridge.

Prince William and Prince Harry similarly adopted part of their father’s title as their last name when they enlisted in the military under William Wales and Harry Wales, The Independent reports. Prince Charles is, of course, the Prince of Wales.

Soon we will all find out what William and Kate’s third child will be named, because the Duchess of Cambridge is reportedly due any day now.

This article originally appeared on Harper’s BAZAAR US.