Prince William and Kate's family grew by one when they welcomed their third child, Prince Louis Arthur Charles to their brood.
The Duke and Duchess of Cambridge were already parents to four-year-old Prince George and Princess Charlotte, who turned four on May 2.
As royals, William and Kate don't necessarily have the same worries that regular parents do. They have nannies to lend a hand and all the baby supplies they could ever need.
However, when it comes to raising their children, their job is by no means easy.
Since the kids have to grow up in the spotlight, the royals have to abide by strict rules that stipulate how they should behave, dress, and talk.
Here are 19 that William and Kate will have to use on George, Charlotte and even little Louis.
1. Princes George and Louis can't wear long pants
Prince George is one of the preppiest kids around, and there's no doubt that his brother Prince Louis will soon be dressing up like him.
However, over the years many people have noticed that Prince George is never seen wearing long pants, only shorts.
Turns out, there's a dress code that dictates how members of the royal family should dress, and it stipulates that boys must only wear shorts until they turn eight years old.
"Trousers are for older boys and men, whereas shorts on young boys is one of those silent class markers that we have in England," explains etiquette expert William Hanson.
"Although times are (slowly) changing, a pair of trousers on a young boy is considered quite middle class "“ quite suburban. And no self-respecting aristo or royal would want to be considered suburban. Even the Duchess of Cambridge."
2. Arts and crafts are a must
Kate and William both hold degrees in art history. Prior to getting married, Kate even held a number of jobs that required her to use her creativity, including photography and design.
These days, she is making sure to consistently nurture creativity in her children by doing arts and crafts with them.
According to sources close to the family, Kate is a huge proponent of homemade gifts, so she encourages the kids to make hand-made gifts for their relatives, including the Queen.
3. They have to speak multiple languages
Education is very important to the royal family. Since they travel to all corners of the world as part of their duties, it's almost a requirement to know at least one language other than English.
Nearly everyone in the family can speak French. Prince Charles and William are also fluent in a few more languages including Welsh.
Now, it's the young children's turn to jump on the multilingual train.
Kate revealed that George has already started learning other languages, and can already count to ten in Spanish. His sister, Princess Charlotte, isn't trailing too far behind.
4. Media training is mandatory
Prince Louis, the newest member of the royal clan, doesn't have much to worry about right now, but his siblings are already being groomed to know how to behave when the cameras are rolling.
Of course, Kate and William will be doing all the talking on their behalf for now, but as they get older, they will need to be taught how to talk to the press.
Right now, they will still need to learn how to learn other simpler skills like how to properly do the signature Windsor wave.
5. Nicknames cannot be used in public
Despite the fact that the media often calls the Duke and Duchess Will and Kate, they're actually not allowed to use these names while carrying out official royal duties. This is why hear William always refer to Kate only as Catherine.
Prince Harry, whose real name is Henry, appears to be the only exception to this rule.
George and his siblings should always be addressed by their full names and titles when they're in public.
However, anything goes when they're inside the palace walls.
The Queen's close friends call her "Lilibet," her husband Prince Philip calls her "cabbage," and George gave her the nickname "Gan Gan."
6. Babies must be baptized
Several days or weeks after a royal baby is born, they must be christened by the head of the Church of England.
The ceremony requires the newborn to wear the same traditional gown worn by the royals born before them. The current gown is a replica of the one used in 1841 when Queen Victoria was on the throne.
It has since been worn by 62 royal babies over eight generations.
7. Maintain proper posture at all times
It's important for everyone to have good posture, but for royal children (and their parents), slouching is a no-no at all times.
Maybe it's allowed when they're in the comfort of their home, but when in public, they're expected to stand with their backs straight, feet shoulder width apart, and their chins slightly lifted.
They're also not allowed to put their hands in their pockets, no matter how much they want to do it.
8. Kate has a strict screen time limit
Just because they're heirs to the British throne doesn't mean George, Charlotte and Louis will get spoiled.
In an attempt to give them as normal of an upbringing as possible, William and Kate don't give their children everything they want, especially not excessive screen time.
The Duke and Duchess of Cambridge have banned their young children from using most electronic gadgets, including tablets.
"They're very much seen as Mummy and Daddy's toys, not for children . . . As two people who grew up without gadgets for entertainment themselves, William and Kate are firm believers in toys, outdoor play, and encouraging an active imagination. They're very much a normal family," according to a close source.
The kids are still allowed to watch children's shows and movies, but of course, there's a limit to how many hours a day they can do that.
William once revealed that George loves The Lion King, the LEGO movies, and British show called The Octonauts. As for Charlotte, a source close to the family said she enjoys Disney Princess movies.
9. Monopoly is not allowed at game night
The royal family are big fans of board games; they even play them at Christmas.
However, there is one game you will never see them play and it's Monopoly.
Back in 2008, Prince Andrew said that they're "not allowed to play Monopoly at home. It gets too vicious."
Since the game elicits too many fights, William and Kate will most likely not introduce it to their brood.
10. Selfies are not allowed
Royals are barred from giving out autographs, taking selfies, or even hugging those who aren't family.
Obviously, these rules have been broken many times, but when it comes to the youngest members of the family, the rules will have to be taken much more seriously.
It's going to be harder to enforce this rule as they get older and become teenagers, but it's one way to ensure that they have control over where their photos end up.
11. Christmas will be spent at Sandringham House
Sandringham House is smaller than the other houses, so only the Queen's closest family members are invited to join her.
They take part in a number of activities, including a charity soccer game, exchange gag gifts, play charades, attend church, and listen to the Queen's speech.
So if Kate wants her children to spend time with the Middletons over the holidays, she will have to divide her time between Sandringham and her parents' house.
12. Presents are opened on Christmas Eve
On Christmas Eve, the family gathers in the White Drawing Room for a special afternoon tea. Afterwards, the children will help decorate the Christmas tree and exchange presents, including funny gag gifts.
The royals stick to this European tradition of opening presents on Christmas Eve because they are usually busy attending two services at St. Mary Magdalene Church on Christmas morning, and partaking in more feasts.
13. They can't eat shellfish
You can't be a member of the royal family and do whatever you like. There's strict protocol to abide by even when it comes to what your diet consists of.
There aren't a lot of things that are off-limits, but the royals have been historically known to avoid eating certain foods when dining out.
You will probably never catch George, Charlotte or Louis eating shellfish at a restaurant because it poses a high risk for food poisoning.
They will also steer clear of rare meat, tap water in foreign countries, as well as foods that are too spicy or exotic.
14. Gifts must be accepted graciously
People love to shower the royals with gifts like edible treats to plush toys, and other small trinkets.
It's considered rude to reject gifts, so they must graciously accept them.
The family keeps track of all the items they have received, and every year, they release a list with details about the gifts, including where and who gave it to them.
This year's list includes stuffed animals and hobby horses for Prince George and Princess Charlotte.
If the gifts are under $200, they can be used or placed in storage for up to five years. If they're of higher monetary value, they can be added to the Royal Collection, or loaned/ donated to an organization.
15. They must know which order to enter a room
Surely, George and Charlotte understand which one of them is older, but they're still too young to know the order of who's next in line to the throne.
This is something their parents will have to teach them because when they're part of a procession, the order of precedence is key.
George, Charlotte and Louis can only enter a room or be seated after The Queen, Prince Philip, Prince Charles, Camilla, Prince William, and Kate.
Being as young as they are, they're sticking by Kate and William's side for now, but it won't remain this way for too long.
16. No political affiliation allowed
Members of the royal family aren't allowed to have any political views or run for office. They can't comment publicly about political affairs and they are not allowed to vote.
William and Kate will have to teach their children to be diplomatic early on, so they don't accidentally get caught up in political controversies later in life.
17. They must stop eating once the Queen stops
This probably isn't a rule that is followed at home, but when at a special dinner, everyone has to stop eating once the Queen puts her cutlery down, even the kids.
I'm sure when the little ones are really hungry Kate will sneak them a snack to munch on, but it's a rule they try to impose as much as possible so it is ingrained in them as they grow up.
18. They can't leave the house without security
There's no sneaking out of the house late at night to hang out with friends, because the royal children have to have security tailing them at all times.
Even while at school, George and Charlotte have a permanent security team protecting them. It won't be any different for Louis.
The security detail even has multiple alternative routes mapped so George and his sister won't have to take the same one to school every day.
19. They must attend the annual Trooping the Color ceremony
Trooping the Color, the Queen's official birthday ceremony, must be attended by all able members of the family including the small children.
Every year, the entire family gathers on the famous Buckingham Palace balcony to watch the Royal Air Force fly and wave at the crowd below.
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