Julia Roberts 'bullied sister for being overweight'

In her first interview, Julia Roberts' half sister Nancy Motes has revealed details about their tense relationship growing up.

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Speaking with New York Daily News, Roberts' younger sibling Nancy - who is daughter of Julia's mother Betty Lou and stepfather Michael Motes - says her older sister regularly made her feel upset about being overweight.

Julia Roberts with her Golden Globe in 1990. Source: Getty

"When I was in high school and she was an adult, she would just let me know that I was definitely overweight," said Motes, who was in eighth grade when her sister landed her iconic role in Pretty Woman.

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"She would make it quite clear to me and in a not-so-nice a manner."

"It just makes me feel incredibly hurt and very sad."

With a family full of stars, 37-year-old Nancy - who is now a production assistant on TV show Glee - said her hope to follow in her family's famous footsteps was dampened by her sister's discouraging words 'because she was overweight', according to NY Daily News.

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"My weight has fluctuated my entire life. So I just got a lot of criticism from Julia, which was very discouraging for me."

Julia Roberts with Mel Gibson in 1997. Source: Getty

Once weighing 136 kilograms, Motes underwent gastric bypass surgery in 2010 to become 70 kilograms and although she hopes she can reconcile with her Eat Pray Love star sister, Motes isn't confident her weight loss will 'fix' their relationship.

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"I think we’re both trying to change our opinions of each other," Motes said.

"It’s a work in progress. It’s not going to be fixed overnight, nor do I think it’s going to be fixed at this point by me just getting skinny."