From affairs to wild parties and doubts over Khloe’s paternity: New book makes shock claims about the marriage of Robert and Kris Kardashian

YOU probably think you know everything there is to know about Kim, Kourtney, Khloe and Rob Kardashian.

But there is a little-known prequel — the story of her parents Robert and Kris’ tempestuous marriage, which was allegedly marked by rampant philandering and scandal.

Author Jerry Oppenheimer is to release a book called The Kardashians: An American Drama next month, where he will lift the lid on the relationship, which ended shortly after Rob was born.

And in it he reveals how Robert had an infatuation with Elvis Presley’s ex-wife Priscilla, how Kris’ was repeated unfaithful and how Robert allegedly confessed to his pastor that Khloé wasn’t his biological daughter.

The book starts by describing how Robert came to fame as a supporter of pal O.J. Simpson, when he served as a legal consultant on the “dream team” that won the athlete a not-guilty verdict in his infamous 1995 murder trial.

Robert, a born-again Christian of Armenian descent, was born in 1944 to a wealthy Los Angeles family and he would later inherit the clan’s meatpacking empire.

Despite standing a mere five foot eight and being stricken with a thick white hairline streak in his otherwise jet-black mane, he was considered one of Beverly Hills’ most eligible bachelors in the 1970s.

Meanwhile Kristen 'Kris' Houghton came from San Diego and was raised by her tough-as-nails maternal grandmother after her alcoholic father left when she was seven.

At 17, Kris wasn’t dreaming about prom or college, but looking for a man.

High-school pal Joan Zimmerman thought Kris’ mum, Mary Jo, was “kind of pimping her out” when she started a relationship with golf pro Cesar Sanudo, who was more than 10 years her senior.

That ended when Kris met Robert — who thought the teenager looked like a young Natalie Wood - at a horse-racing track and cheated on her boyfriend with him.

As Jack Spradlin, a friend of Sanudo’s, said: “Kris saw a far better financial opportunity with Kardashian than with Cesar.”

Still, Robert thought Kris was too young for things to be serious, and soon dumped her for Priscilla Presley.

A worldly Presley told Robert how to dress and what kind of car to drive. The relationship, however, would never escape the specter of her famous ex.

Robert “complained to a friend that while he was making love to Priscilla, she would get incoherent phone calls from [her ex-husband] Elvis ‘and she would put the receiver on the pillow between them and let him listen,’ ” Oppenheimer writes.

Robert aimed to turn Priscilla into “the perfect Armenian housewife but she was insulted and soon, she told him: “I’m not going to marry anyone until Elvis dies.”