"The only comfort we feel now is that Robert is with his mother," twins Timolin and Casey tell PEOPLE exclusively

By Linda Marx
August 16, 2017 09:30 AM

Natalie Cole’s younger sisters, twins Timolin and Casey Cole, are devastated over the sudden death of their nephew Robert Yancy, who was found dead Monday in California.

“We are at a loss for words,” the twins, who carry on the family’s legacy through their work with Nat King Cole Generation Hope, tell PEOPLE exclusively.

“He was deeply saddened over the loss of his mother,” adds Timolin of Robert, who was Cole and late singer and producer Marvin Yancy’s only child.

“When Natalie died, he lost the most important person in his life. It was very hard for him.”

Credit: Courtesy Maureen O Connor

The twins, 56, tell PEOPLE that Robert had been getting his life back in order following the death of his mother from congestive heart failure in 2015. He was working and performing much like his late parents and grandfather Nat King Cole.

“He bought a new place to live and was super excited about celebrating his 40th birthday on Oct. 14,” Casey tells PEOPLE. “He didn’t go to the doctor much, but he was feeling good. He was so busy with his life that he neglected that part.”

Credit: Amy Graves/WireImage

The twins believe Yancy suffered a “cardiac arrest” but they won’t have final confirmation until autopsy and toxicology reports are released.

“His dad died early, too, but Natalie never mentioned concerns over her son’s health,” says Timolin. “The only comfort we feel now is that Robert is with his mother.”