It's said that The Queen has a new favourite relative — and it's the Countess of Wessex.

Sophie Wessex celebrated her 57th birthday today. Queen Elizabeth was sure to pay tribute to her beloved daughter-in-law on social media.

Queen Elizabeth's birthday tribute for Sophie Wessex

On Twitter, the Queen wrote to Sophie: "Wishing The Countess of Wessex a very Happy Birthday today!" She added a balloon emoji for flair.

For the tribute, the Queen chose a nice photo of Sophie cradling an adorable puppy. The Black Lab is actually a guide dog with Guide Dogs UK.

Sophie, now 57, is married to Prince Edward, the youngest of the Queen's four children. Sophie and Edward have two kids of their own: Lady Louise, 18, and James, 14.

Sophie: The Queen's favourite in the Royal Family?

As for that "favourite" relative claim... It had long been said that Prince Andrew was the Queen's favourite child, but he has fallen from grace amid a scandal over allegations of sexual abuse.

Recently, a Palace courtier told The Sun that the Queen's favourite child is not one of her own, but her daughter-in-law, Sophie.

British Royals Who Lead Normal Lives

A royal breath of fresh air!

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Insiders and commentators also claim Sophie has stepped up for the Queen following the loss of her husband Prince Philip.

She has even been called Queen Elizabeth's new "rock." Quite the honour!

Happy birthday, Sophie!