Someone has issues with DADDY....

In the Jan. 31 issue of Star, on sale now, we exclusively reveal that the pop singer is rewriting her family history — insisting she doesn't know her dad — when not only does she know him, but she also had a relationship with him!

The over-the-top performer has publicly spoken out about not having a father, saying that it never bothered her not knowing his identity. But Star has an exclusive interview with her dad, Bob Chamberlain, a musician and successful engineer, who has no idea why Ke$ha and her mother say he doesn't exist, especially when he has letters his daughter sent him starting “Dear Dad” and pictures of them together through the years.

"I was in her life from the time she was born until she was 19 years old," says Bob, who is speaking out for the first time about how stunned he is to be erased from her history. "The contact ended, and I have no idea why."

Devastated by the whole situation, he says: "Maybe someone around her thought it would be better to perpetuate those myths; I don't know."