Prince William and Princess Eugenie may have unintentionally shown during the "Together at Christmas" service at Westminster Abbey last year that they do not share a close bond.

Body language expert Jesús Enrique Rosas, who goes by The Body Language Guy on YouTube, examined a video of the cousins to help him "assess the current relationship inside the Royal Family." It showed their bond or lack of it especially when the royals greeted each other before the service started.

"What's relevant about this clip is you can see Prince William and Catherine, Zara Tindall and Princess Eugenie and Beatrice. Everyone pay close attention to the dynamics between the York sisters and the Duke and Duchess of Cambridge," he said and pointed out how the Cambridges were very warm towards Zara.

The Duke and Duchess of Cambridge closely embraced Zara and Rosas explained how the interaction showed their bond with each other. He said, "There is closeness, there's his open and relaxed hand, you can see his inner elbow is basically matching the arm of his cousin. There's enough contact to signal that they feel comfortable with each other and they are happy to meet."

Rosas said they even had "full contact between their heads and faces. Whereas, Prince William behaved differently with Princess Eugenie. Instead of a hug, he simply placed his hand on her back and she did the same to him.

"I'm sure by this point you've already noticed...William usually grabs people's arms to signal goodwill. We already saw him embracing Zara, so it could have made sense if he did the same thing with Eugenie, but he didn't."

He added, "For me, the biggest tell is Eugenie's taps on William's side. They have absolutely no pressure... and they keep a personal distance between them. Extremely formal, no warmth at all."

Rosas found it "interesting that William did not greet her in the same way as he did with Zara." It is said that Kate Middleton did not even greet Princess Eugenie. He said the lack of warmth in the Duke of Cambridge and his cousin's greeting showed they are "not on the best terms." It is unclear why, but it is believed that this is because the princess is good friends with Meghan Markle and is known to be very close with Prince Harry.

Zara Phillips and Mike Tindall Royal Wedding
Prince William (L) and his wife Catherine (R), the Duchess of Cambridge, and Princess Eugenie (C) leave a drinks reception on the royal yacht Brittania in Edinburgh, Scotland July 29, 2011. The couple and other members of the Britain's royal family attended the reception for Zara Phillips, the grandaughter of Britain's Queen Elizabeth, and England rugby player Mike Tindall who marry each other on Saturday. Reuters