Justin Bieber has found an unlikely supporter for his controversial signature in the Anne Frank House guestbook: her stepsister!

Bieber was universally slammed by the internet for writing that he hoped Anne "would have been a Belieber," with the Twittersphere calling him a "moron" and a "douche," among other names. The Anne Frank House has since gone on to defend Bieber, but it's her stepsister Eva Schloss who has become his most unlikely ally in the backlash.

Not only did she call the fuss surrounding Justin's signature "so childish," but Schloss claimed that Anne likely would have been a Belieber had she been alive today.

"She probably would have been a fan. Why not?" said Schloss in an interview with The Telegraph. "He's a young man and she was a young girl, and she liked film stars and music," Schloss said. "They make a lot of fuss about everything that is connected with Anne Frank."

Not only does the Anne Frank House note that Frank was a fan of celebrities, but it turns out that one of the tour guides may have implanted the whole Belieber idea into the singer's head. "One of the guides pointed out that Anne was a big fan of pop culture of her time and that she might have been a fan of his, which led to what he wrote," said a source to E! News.

Photographs of Bieber shadowboxing inside the museum have also surfaced, igniting further anger towards the singer. He has yet to directly acknowledge the controversy, choosing instead to post two shirtless photos of himself on Instagram.

Luckily, Bieber's recent European concerts have been generating far less controversy than his cultural visits. He's scheduled to play the last of three concerts tonight in Oslo, Norway before heading to a gig this Saturday in Copenhagen, Denmark.