Life & Style has learned exclusively that Tatum O'Neal has just been cast as Dakota Fanning's character's mother in The Runaways. Tatum, who is the daughter of Ryan O'Neal and stepdaughter of Farrah Fawcett, is best known for being the youngest actress to win an Academy Award.

The Runaways is a biopic of singer Joan Jett and also stars Twilight lead Kristen Stewart.

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