The Saturdays singer, who shares two daughters with husband Marvin Humes, was chatting to Giovanna Fletcher on her podcast Happy Mum Happy Baby when she made the revelations.
“I’ve never told anyone this before,” she said. “Two years ago, I was at our management’s Christmas Party and Love Island’s Kem was there.
“He was chatting away and said, ‘I got to talk to you… as soon as I became a celeb I promised my friend Lili that I would talk to you as she’s your sister from your dads side.'
CHECK OUT Rochelle Humes' sisters
Rochelle Humes sisters STACKED
1 of 5Rochelle Humes
Rochelle poses with her sisters Sophie and Lili Piper – don't they look the spit of each other?
2 of 5Rochelle Humes
Posing up a storm with youngest sister Sophie before a night out.
3 of 5Sophie Piper
Sophie preparing to set off around the world to "live in the sun" for the rest of the year
4 of 5Rochelle and Lili Piper
Rochelle and Lili Piper as they holiday together in Dubai
5 of 5Sisterly love
Celebrating Rochelle's 30th birthday was some sisterly love.
“I knew of her and met up with her when I was five, but it was so complicated as they were a lot younger and my dad wasn’t involved.”
Rochelle has since formed a close bond with Lili and says they’ve spoken “every day” since their reunion, and have enjoyed nights out and holidays together.
Rochelle regularly shares photos of her and her family on social media – and every time she does, fans are flabbergasted by how similar they look.
In March she posted a photo of her, Lili, and youngest sister Sophie – who she has “always been close to” – and fans could hardly tell the difference.
“Legit thought they were all Rochelle then hahahah,” said one commenter, while another added, “Wow you are all the spit of each other 😘👌”.
And last year she posted an throwback picture of herself from school alongside a friend she’s still friends with now (adorbs), and was quick to point out how much she looked like eldest daughter Alaia.
“Braidin’ell!!!! 😭 Me and my bestie @aimeefordkingwhen we were bambinos,” she captioned the post. “🤗 I am the DOUBLE of Alaia 😧”.
Strong genes!