There's a reason Princess Charlotte always wears a baby doll dress

Just like Prince George is always spotted wearing shorts and high socks, at 4-years-old, Princess Charlotte has also developed her very own style staple: baby doll dresses.

No matter the occasion -- whether it's a high-society wedding or running around at a polo match -- the royal tot is never without her smocked dress. It's a fashion that Charlotte has inherited from other royals, from Princess Anne to Princess Eugenie, specifically during the royal family's official public appearances.

Take a look:

"If you look at photos of young royal girls – from Princess Anne to Charlotte, you will notice that they tend to wear smocked dresses as little girls when they are in public with their parents," explained royal expert Marlene Koenig to Harper's Bazaar.

Why? Like anything the royals do, there's a reason Duchess Kate and Prince William have chosen the rather traditional-style frocks for their daughter: To prevent her from looking "out-of-date."

Explained designer Rachel Riley previously to the Telegraph, “If they wear very simple things, it’s about the child, and it’s timeless in that you can’t really date a specific photo or put them in something that seems out of date. I think they are going for clothing that is classic and timeless, rather than clothes that draw attention to them.”

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Just like Prince George is never photographed in trousers and Princess Charlotte is spotted in Prince Harry's hand-me-down shoes, her dresses give off the same message.

Most likely, Char and George are dressed in more casual clothes when away from the public eye.

"I expect that when the kids are at home, playing in the nursery or in the backyard, they are wearing more casual clothes," Koenig continued.

And like her mom Duchess Kate and aunt Meghan Markle, the Princess Charlotte effect is very, very real. At only 4 years old, she has an expected worth of $4.3 billion and is predicted to bring forth an even bigger contribution to the British economy than Prince George.