The 23-year-old American found international infamy in the aftermath of the killing, which prosecutors say she carried out after a bungled sex game.
As the lengthy judicial process continues to play out in the Italian city of Perugia, Knox has become the subject of numerous books and films.
Her face has been splashed across the pages of newspapers and magazines around the world.
Her stepfather, Chris Mellas, said: "She thinks it's ridiculous. There are nine books (about her), with another four or five that I'm aware of in the works; two movies in the works right now; seven or eight documentaries that I'm aware of.
"It's absolutely bizarre. We have no interest. The whole celebrity thing is just ridiculous."
He spoke out as Knox spent a fourth Christmas behind bars for a crime she maintains she had no involvement in.
And as her appeal process carries on, her family said this may be her final opportunity to prove her innocence until she is 30.
Mr Mellas, 36, who has moved to Italy to be near his stepdaughter, said: "This is the last chance in probably seven years to have the verdict revoked."
If Knox fails in her current appeal, she will be entitled to a second appeal under Italian law at the country's highest court in Rome.
But Mr Mellas said: "The Supreme Court doesn't rule on the basis of merit, it only rules on technical issues. They would never say: Your previous two cases are flawed."
The University of Washington student was found guilty last December of killing Ms Kercher, 21, from Coulsdon in Surrey, with her former lover, Raffaele Sollecito.
Although sentenced to 26 years in prison, she has continued to protest her innocence from behind bars and support for her has poured in from around the world.
The semi-naked body of Miss Kercher was found in November 2007 with her throat slit in her house in Perugia, where she was studying on her year abroad.
Prosecutors said Sollecito held her down while her housemate Knox stabbed her. Rudy Guede, 22, from the Ivory Coast, was jailed in October 2008 for 30 years for the murder and sexual violence.