Bella and Gigi Hadid have a stunning secret half-sister who has become part of their inner circle after meeting for the first time less than two years ago.

The Daily Mail can exclusively confirm that the models’ younger sibling is Aydan Nix, a 23-year-old who graduated from the Parsons School of Design in Manhattan earlier this month.

Her mother became pregnant after a brief romance with Mohamed Hadid, Bella and Gigi’s multi-millionaire real estate developer father.

Aydan and her mother’s link to the superstar family have been kept under wraps for almost two decades, until now. 

Gigi and Bella Hadid on Thursday confirmed Aydan is their half sister and they have ‘cherished this unexpected and beautiful addition to our family’.

The Daily Mail understands that Mohamed, now 76, maintains a relationship with Aydan in private but has never acknowledged her publicly. 

Aydan, who grew up in Orlando, Florida, studied Fine and Studio Arts at Parsons and  connected with the sisters when she was studying abroad in Paris last year. 

Since then, she has been photographed with them on multiple occasions.

They have been spotted on nights out in New York and during bikini-clad trips to the beach.

Family members told the the Daily Mail that the newfound sisters have kept in contact and were ‘becoming closer’.

They follow each other on social media and appear on each others’ Instagram stories.

However, despite the growing bond, none of the women publicly identified each other as siblings – until Thursday. 

‘Over 20 years ago, our dad, while single, had a brief relationship that led to a pregnancy,’ the family said.

‘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. 

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

‘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.’

While the willowy Aydan shares the Hadids’ angular cheekbones and signature torso, her upbringing was worlds apart from that of Gigi, 29, and Bella, 28, who between them have graced the pages of international Vogue magazine more than 85 times.

Aydan was an honor student and cheerleader at a prep school in Orlando, where she took a keen interest in French and fashion. 

Though raised in a comfortable home with her mother and stepfather, she held down a summer job delivering Domino’s pizza.

After high school, Aydan moved to Manhattan to pursue a career in fashion. 

In addition to internships with photographers and stylists, she worked as a commissioned sales associate at the vintage clothing store Harley’s.

Aydan was raised by her mother, Terri Hatfield Dull, in a suburb of Orlando – far from the glamorous world of her siblings.  

Mohamed Hadid had met Dull shortly after his divorce from Real Housewives of Beverly Hills star Yolanda Hadid in 2001. 

Yolanda is the mother of Gigi, Bella, and their younger brother Anwar. Mohamed also has two daughters, Marielle and Alana, with his first wife, Mary Butler.

The Palestinian-American real estate tycoon had a brief romance with Dull that ended shortly before she discovered she was pregnant.

The Daily Mail understands that Mohamed always knew about Aydan but has not provided financial support. 

She was raised by her mother, who has worked as a mortgage loan originator and has since married. 

Now embedded in the very industry her sisters dominate, Aydan is carving out her own niche as a designer, stylist and aspiring influencer. 

A source close to the family confirmed that Mohamed maintained a cordial and pleasant relationship with Aydan. 

While he follows her on Instagram, he has conspicuously excluded her name from public interviews and social media posts. 

In a Father’s Day message in 2024, he discussed his ‘five children’, omitting to mention Aydan.

He had been expected to attend his daughter’s graduation in May but reportedly canceled about a week beforehand.  

A family source told the Daily Mail that while Mohamed has fondness for Aydan, he so far had not been ready to publicly acknowledge her as his sixth child. 

‘There’s mutual respect,’ the source said. ‘But there’s also discretion.’

At the graduation ceremony in Brooklyn on May 16, Aydan celebrated with classmates and was seen posing for photographs.

A proud Dull posted pictures on Instagram of her daughter in a red robe, mortar board and sunglasses.

Aydan also wore a black and white keffiyeh scarf, perhaps a nod to her father’s Palestinian heritage or as a gesture of protest over the war in Gaza. 

The graduate marked the occasion with her own social media post, captioned: ‘WTF………. post grad ……..’