Khloe Kardashian's paternity has been called into question several times over the celebrity's lifetime. Rumors surfaced that her mother Kris Jenner was sleeping with both Robert Kardashian and O.J Simpson, which lead the Kardashian family to question whether Khloe was Robert's biological daughter. These rumors have surfaced once more as Jerry Oppenheimer releases his book "The Kardashians: An American Dream."

O.J Simpson refused to take DNA test

According to Radar Online, when the rumors first surfaced that Robert Kardashian was not the biological father of Khloe Kardashian the father opted to take a DNA test.

The other celebrity in question was O.J Simpson as there were rumors that Kris Jenner was sleeping with both Simpson and Kardashian. Simpson refused to take the DNA test to prove that Khloe was not his daughter.

This has raised suspicions among the media and fans of the Kardashian's as without O.J Simpson's DNA there would be no conclusive evidence that Khloe did not share any genetics with the former NBA star. However, shortly before his premature death Khloe's father Robert Kardashian signed a declaration in which he stated that he had four biological children.

According to Robert Kardashian's ex Jan Ashley, Robert had confided in her that Khloe was not his biological daughter. Jan came to Khloe with this information and wanted to go public with it 10 years after Robert Kardashian had passed away.

This deeply upset the Kardashian and she told Jan Ashley that she could spread whatever gossip she wanted about her but to keep her father out of it.

The rumors are investigated in new book

According to the Daily Mail, Jerry Oppenheimer investigates these rumors in depth in his upcoming book about the Kardashians titled "The Kardashians: An American Dream." He goes through the claims that have been made over the years about Khloe Kardashian's paternity and states that the rumors that Kris Jenner was sleeping with O.J Simpson remain unclear.

The book also investigates the claims made by close friends of Robert Kardashian that the father of Kourtney, Kim, and Khloe told them Khloe was not his biological child. According to the Daily Mail, Robert Kardashian also confided in his local pastor about the secret.

There has been no comment from either Khloe Kardashian or Kris Jenner about the rumors. The rumors about her paternity have always been a struggle in Khloe Kardashian's life and the release of the book by Oppenheimer is sure to open old wounds.