Kate Middleton Goes on Vacation -- Without Prince William!

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Kate Middleton may have married into the royal family, but she's still quite independent!

On Wednesday, the 30-year-old Duchess of Cambridge flew first class from London Gatwick Airport to St. Lucia with her parents, Mike and Carole, and siblings Pippa, 28, and James, 24, Us Weekly can exclusively report.

Noticeably absent? Kate's husband of nearly a year, Prince William, 29.

Once the Middletons arrived in the Caribbean, they were taken to the ultra-private island of Mustique. The family returned to their favorite tropical locale to celebrate Carole's birthday; she turns 57 on January 31.

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The Middletons last visited Mustique in August; Kate was unable to join her family at the time.