Supermodels Gigi and Bella Hadid announced they have a 23-year-old half-sister, Aydan Nix, from their father Mohamed Hadid's brief relationship with Terri Hatfield Dull over two decades ago. Aydan, who recently discovered her biological connection through a DNA test, has been welcomed into the family. The Hadids request respect for Aydan's privacy as she pursues a career in the fashion industry.

Prepared by Emily Rhodes and reviewed by editorial team.