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Dayum!Taylor Swift, Zac Efron, and More Celebrities Who Have Really Hot Brothers – See Then-and-Now Pics

It's always a bit jarring when a celebrity's sibling goes from being cute to really, really hot. Such is the case for these celeb brothers.

RELATED: They're All Grown Up! See What Celebrities' Younger Siblings Look Like Now

Click through the gallery to see Taylor Swift, Zac Efron, and more stars' siblings transform right before your eyes.