Princess Charlotte looks like a young Prince William in her 6th birthday portrait

• The royal family shared a new picture of Princess Charlotte, who turns 6 on Sunday.
• She's the second child and only daughter of Prince William and Kate Middleton.
• The Duchess of Cambridge is known for taking official royal portraits of her family.
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Princess Charlotte celebrates her sixth birthday on Sunday.

Kensington Palace shared a previously unseen photo captured by the Duchess of Cambridge, who's the first royal family member to take official portraits of her family members.

Princess Charlotte is the second child and only daughter of Prince William and Kate Middleton. Princess Charlotte's older brother, Prince George, turns 8 in July, and the youngest Cambridge kid, Prince Louis, turned 3 in April.

Princess Charlotte resembles many of her royal relatives – some photos of her look strikingly similar to childhood photos of Middleton, her late grandmother, Princess Diana, and even distant royal cousins.

In some photos, Princess Charlotte has seemed to resemble her great grandmother, the Queen, when she was still Princess Elizabeth.

In her sixth birthday photo, however, she shows an uncanny resemblance to her dad, Prince William, when he was around her same age.

Here, Prince William, around age 7, is pictured in 1989 leaving a Thanksgiving service at his school.

The two seem to have similar smiles and facial features.

Middleton took Princess Charlotte's portraits outside the family's home in Norfolk, England.