Beyoncé’s dad is battling breast cancer. Mathew Knowles shared the startling news in a teaser for “Good Morning America” on Tuesday, ahead of his sit-down interview. Taking a seat with Michael Strahan, the 67-year-old reveals his diagnosis for the first time to the world. In the short clip, the “GMA” host is heard asking Beyoncé and Solange’s father about breaking the news to his famous daughters. “How was it to tell your family about the diagnosis?” Strahan asks. Mathew Knowles is best known for managing Destiny’s Child during their career, but has been out of the public eye after Beyoncé cut ties with him professionally when she went solo.