• Kate Middleton shares Prince George's budding interest in playing tennis.

Kate Middleton shares Prince George's budding interest in playing tennis. (Photo : Getty Images/Ben Curtis)

The Duchess of Cambridge is rumored to be feuding with her sister Pippa Middleton following the latter's engagement to James Matthews and what could eventually become her relationship with Matthews' brother Spencer.

According to Life & Style, Kate is worried about what may happen to Middleton when Spencer becomes her brother-in-law. After all, Spencer has gone on to appear in a number of reality TV shows where he confessed to experimenting with different types of drugs.

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"Spencer has slept his way around London and left a lengthy trail of angry women in his wake. Kate's concerned. The last thing she wants is for William's family to turn against her because of Spencer's actions," a source told the publication.

Additionally, Kate is also rumored to be concerned over the possibility of Spencer revealing some of the Middleton family's biggest secrets.

"During a heated discussion, Kate expressed how unhappy she is because of James' 'uncouth' family connections. She believes they will try to cash in on the royal family. Kate goes out of her way to portray herself as the perfect princess and is petrified the fame-hungry Pippa is going to ruin everything," the source added.

Meanwhile, InTouch Weekly previously reported that Kate and Middleton are having issues with each other because the latter could no longer take the former's judgmental attitude.

"After years of private drama, clashing views about courting attention and fresh concerns about a wild brother-in-law to be, Pippa doesn't want Kate in her wedding party. She's fed up with Kate's judgmental attitude, and doesn't want her to be a bridesmaid unless she starts to chill out," an insider said.

However, Gossip Cop debunked the rumors that siblings are fighting with each other and said that Kate and her sister are in good terms.

In other news, Kate and her husband Prince William just returned to their home after vacationing in France. During their short trip, the royal couple was spotted spending a night at the prestigious Hotel du Palais in Biarritz.

As of late, there are ongoing rumors that Kate is pregnant with twins. However, the couple hasn't confirmed or denied the reports.