The website also reports that law enforcement are treating his death as by natural causes, pending the toxicology report. He reportedly worked in the music industry.
According to People Magazine, TMZ reports Yancy was found by a friend in his San Fernando Valley, California apartment.
Yancy's father also died from a heart attack when he was just 34-years-old. The publication also speculated that Robert's cause of death might have been hereditary, due to the similar circumstances behind his parents' deaths.
Natalie Cole - an Evening with Brent Shapiro Foundation Summer Spectacular in Beverly Hills, September 14, 2014.
It was made clear to the family that drugs, which Robert never used, were not involved in his death.
Yancy and Cole-daughter of the late singer Nat (King) Cole-were Wednesday in 1976.
Natalie Cole's son died on Monday, a rep for the Cole family confirms to ET.
"Here is a woman who has been in the business for four decades, had 21 Grammy nominations and won nine Grammys. We will find solace in her legacy as well as her endless fans around the world".