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When did Demi Moore‘s oldest daughter, Rumer Willis, get so hot? The two — seen at the "House Bunny" premiere Thursday night — now look like sisters!

Apparently, it’s happened gradually. Check out Rumer’s evolving look (above, wearing Reem Acra) over the past three years. She’s gone from awkward to positively elegant, like a true Hollywood metamorphosis, gosling to swan.

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Photos: WireImage