Gigi and Bella Hadid speak out after they discover stranger is actually their biological sister

Supermodel sisters Gigi and Bella Hadid have made a shock announcement after discovering that they have a long-lost sister.

For the last 23 years, the Hadid family has kept a heavily guarded secret - that their father, Mohamed Hadid, struck a 'brief romance' with a woman called Terri Hatfield Dull.

Their relationship resulted in Dull being pregnant and keeping the baby - Gigi and Bella's now 23-year-old half-sister, Aydan Nix.

The real estate developer's connection with Dull came shortly after his divorce was finalised with their mom, Yolanda, in 2000.

Twenty-eight-year-old Bella and her 30-year-old sister were completely unaware that they had another sibling, with the discovery coming shortly after Aydan decided to take a genetic test.

Aydan Nix - Gigi and Bella Hadid's half-sister (Instagram/@toospoiled)

The circumstances of the decision to take the test was due to her father passing when she was just 19-years-old, with suspicions raised over whether her dad was her biological father. It was eventually concluded that he wasn't and, shockingly, that she was related to the famous sisters.

The Hadid sisters issued the following statement to the Mail Online: "Over 20 years ago, our dad, while single, had a brief relationship that led to a pregnancy.

"Aydan was born and raised in Florida, growing up with the man she lovingly knew as her father until his sudden passing when she was 19.

"After his passing, she decided to take a genetic test out of curiosity, and that’s how she discovered a biological connection to us.

"We first connected in late 2023, and from that moment on, we’ve embraced Aydan with open arms."

It continued: "She’s spent time with all of us, including our dad, and we’ve cherished this unexpected and beautiful addition to our family.

Gigi Hadid and Bella Hadid walk the runway for the Victoria's Secret Fashion Show, in October last year (Dimitrios Kambouris/Getty Images for Victoria's Secret)

"As siblings, we’ve had many open and loving conversations— with Aydan included —about how to support and protect her.

"Aydan and her family value their privacy, and we fully respect that. We kindly ask others to do the same and honor her wish and right to her anonymity as she continues her life as a young woman in New York."

Aydan has recently graduated from the Parsons School of Design, in Manhattan, and has ambitions to become a designer, stylist and influencer.

Meanwhile, the sisters also have a 24-year-old brother, Anwar Hadid.

Mohamed was married to Dutch model Yolanda Hadid from 1994 to 2000. Identifying as American-Palestinian, he also has two other daughters, Alana and Marielle Hadid, from his first marriage with Mary Butler. They separated in 1992.