Grammy-winning singer Natalie Cole, whose biggest hit came in a virtual duet with her late father, pop legend Nat King Cole, of his decades-old hit Unforgettable, has died at the age of 65, her family said on Friday.The family's statement said Cole died Thursday night at Cedars-Sinai Hospital in Los Angeles from "ongoing health issues."Cole's career spanned five decades in the R&B, soul, jazz and pop genres. In 2015 she had canceled appearances citing medical reasons.The TMZ celebrity news website said Cole, who had struggled in the past with drugs, died from congestive heart failure following complications from a kidney transplant and Hepatitis C, diagnosed in 2008. "It is with heavy hearts that we bring to you all the news of our Mother and sister's passing," the Cole family statement said. "Natalie fought a fierce, courageous battle, dying how she lived - with dignity, strength and honor. Our beloved Mother and sister will be greatly missed and remain UNFORGETTABLE in our hearts forever."The statement was signed by Cole's only child, Robert Yancey, and her twin sisters, Timolin and Casey Cole.