Lizzy, 31, who will soon be seen in LA with mentor Simon Cowell during the Judges' Houses round, has revealed that Robert has been helping her out with her bid for stardom.
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X Factor's Lizzy Pattinson has turned to her famous brother for advice
"I sent him a link to the songs for the Judges' Houses, and he said, 'They sound really cool'," she told HELLO! magazine.
"One of the songs was quite obscure and he thought it was really good.
"I'm surprised how interested he is in it," Lizzy added. "He watched the first episode I was in. He gave me feedback and that meant a lot to me."
When personal assistant Lizzy first auditioned on the X Factor, Simon appeared to recognise her. "Have we met before? You look familiar," he said.
Robert Pattinson has said he is "ridiculously proud" of Lizzy for auditioning for the show
Rather than revealing her connection to Robert, she joked, "Maybe in your dreams", before going on to impress all four judges with her rendition of It Feels Like Home.
The Rover actor Robert, 28, recently revealed how impressed he was with Lizzy for auditioning for the show, saying he wouldn't dare do it, "ever, not in a million years".
"I'm like, so ridiculously proud of her," he told Grazia. "I can't believe she's done it. So it's amazing."