I can't believe the Fannings were originally going to play the sisters!
According to Wiki:
Upon the original creation of the film adaption, Dakota and Elle Fanning were set in place to play Kate and Anna, with Dakota playing Kate and her younger sister playing Anna. This pairing was especially convenient as the girls already closely resembled each other and were used to working together. However, when Dakota heard that she would be required to shave her head for the role, she immediately dropped the film. As a result, Elle dropped too. The two sisters were quickly replaced, with Abigail Breslin taking on the lead role as Anna Fitzgerald.
This is awful! The film would have been disgustingly sweet if these two kids had been cast. And how superficial is Dakota?
Defy gravity!