The couple, who wed at St. George's Chapel in Windsor in October 2018, are also firm friends with Eugenie's cousin, Prince Harry.
It's widely known that the cousins have a close bond and Eugenie took a trip out to the States to see Harry, which was shown during their Netflix series.
What's lovelier is that Harry's daughter, Princess Lilibet, who he shares with his wife Meghan Markle, has a strong resemblance to Princess Eugenie's eldest, August.
Click through the gallery to see how similar the two young royal cousins look…
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Princess Eugenie's eldest son, August's resemblance to Prince Harry's daughter
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Cheeky grin
This photo of little August, who turned three in February, shows him grinning as he runs through an enclosure during a family outing to the zoo.
Eugenie and Jack's eldest is wearing a super cute, chequered shirt with a green t-shirt underneath, while wearing adorable Dr Martens boots, too.
We love how August's face is full of pure joy!
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Princess Lilibet
Prince Harry and Meghan released this photo of Lilibet the year she turned one, and it's the one photo that we think truly shows the resemblance between the cousins.
The youngest of the Duke and Duchess of Sussex is now three so is the same age as little August.
We haven't seen Lilibet in recent times as Harry and Meghan mostly keep their two children away from the spotlight, but we bet they've become even more similar as the years have gone on.
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August's red hair
This photo of August was taken in the summer of 2022 during the Queen's Platinum Jubilee celebrations, so Eugenie's son would have turned one the February prior.
Looking at this photo alongside the photo of Lili at the same age, the two adorable kids' faces are strikingly similar, not to mention the fantastic flame-coloured hair.
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August's resemblance to Prince Archie
Not only does August bear a resemblance to Lilibet, but his waved hair reminds us of Harry and Meghan's eldest, Prince Archie.
We've not seen a huge amount of Archie other than the odd glimpse of him during the Sussexes Netflix documentary, but this photo shows off Archie's adorable curls.
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Big brother duties
Another thing Archie and August have in common? They've both become big brothers and clearly love doting on their little siblings.
Prince Archie, five, no doubt looks out for his little sister, Lili, while August dotes on his younger brother, Ernest, who turned one in May.
This photo was shared by Eugenie after she and Jack welcomed their second child.
August looks like the proudest big brother ever as he places a caring hand on his younger brother's head.
The photo also puts August's curly hair which resembles Archie's waves in full display.
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