Good genes sure run in the Middleton family!  

Pippa Middleton showed off her fit figure while on a family vacation in the Caribbean island of St. Barts on Monday. Yep, they missed the Kardashians by a week -- could you imagine if they had run into each other?!

Kate Middleton's younger sis looked like she was having a blast swimming in the ocean while rocking a bright red bikini. The 31-year-old was also joined by her equally attractive brother, James Middleton, and their mother, Carole.  

Pippa -- who's known for having a strict fitness regimen -- is a huge fan of yoga and has recently started training for both marathons and triathlons. Clearly, the brunette beauty's hard work is paying off because she's got some rock-hard abs! 

While the Duchess of Cambridge was not on-hand for the family festivities, the Middletons did attend the christening for her and hubby Prince William's daughter, Princess Charlotte, just last month at the St. Mary Magdalene Church in Sandringham, Norfolk. 

We can't get enough of Pippa's killer bikini bod -- what do you think about Middleton's fit physique?

Sound off below and click "Launch Gallery" above to see more stars hitting the beach!