The paternity claim was published in this week's Star magazine. Robert's ex-wife Jan Ashley and widow Ellen Kardashian alleged that he said Kourtney was not his child shortly before his death in 2003.
"Khloe is not his kid - he told me that after we got married," Ashley told the publication. "He just kind of looked at me and said [it] like it was a matter of fact. He said, 'Well, you know that Khloe's not really a Kardashian, don't you?' And I said... 'OK', and that was it."
Ellen Kardashian claimed that even Khloe knew she was not like her sisters Kim Kardashian and Kourtney Kardashian and brother Rob Kardashian, adding : "Khloe brought it up all the time. She looked nothing like the rest. She was tall, had a different shape, light hair, curly hair. Didn't look anything like the other three children."
Khloe's mother Kris Jenner has admitted to having an affair while married to Robert, though she called the liason "the biggest regret of [her] life".
Responding to the rumours, Khloe took to her Twitter page on Wednesday, writing "The audacity you have to mention my father's name like this! Should be ashamed of urself."
She added: "I let a lot of things slide but this one is really low... YOU ARE DISGUSTING! (yes you know who YOU are)."
Jenner herself has also commented on the reports, telling E! Online: "So stupid. All so silly. Just another day!!!"
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