Hugh Hefner has three sons: David, Marston and Cooper.
David's mother was Hefner's first wife, Mildred (Millie) Williams. While Marston and Cooper's mother is Kimberley Conrad.
Hefner and Williams met at Northwestern University. The couple got married in 1949 when they were both 23 years-old. Their marriage also produced a daughter named Christie, born in 1952.
David has mostly stayed out of the spotlight and away from the Playboy brand. It's unknown what exactly David does — some reports have said he owns a computer-consulting company, and others have said he is a computer-graphics specialist for independent films.
Hugh Hefner separated from his first wife in 1959.
In 1989, he married Kimberley Conrad who was the Playmate of the Year 1989. The couple got married the same year.
In 1990, their first son Marston was born. And they welcomed another son named Cooper in 1991.
Cooper is perhaps the most well-known of the four children. He is the Chief Creative Officer at Playboy Enterprises as well as the founder and former CEO of the media company HOP (Hefner Operations and Productions).
For the first eight years of his life, Marston lived in the Playboy Mansion. He has gotten into a bit more trouble than Cooper, though.
In 2012, Marston was arrested on suspicion of attacking his girlfriend, Claire Sinclair, a Playboy Playmate. He was sentenced to one year in a domestic-violence program. The court also ordered him to stay away from Sinclair for three years.
Christie, David, Marston and Cooper will all carry on the Hefner name. Know more about them at ibtimes.com and BusinessInsider.com.