Duchess Catherine is obsessed with Keeping Up With the Kardashians.

The 31-year-old royal - who was known as Kate Middleton before her marriage to Prince William - has begun tuning into the show after she learned Kim Kardashian, who, like the duchess, is expecting her first child in July, is a big fan of hers.

"Ever since Kim started mentioning Kate a lot in public, she has started watching Keeping Up With the Kardashians religiously. She thinks the family are hilarious. People forget Kate is just a normal girl who married into royalty and enjoys the same trashy TV shows most people do," a source said.

However, Catherine hasn't been able to get her husband to watch the show with her and he has been "making fun" of her new obsession. "Will doesn't watch the show with her and makes fun of her for liking it so much. It doesn't bother Catherine though. She finds it relaxing and is flattered Kim keeps speaking so highly of her," the source added.