Kunis' brother Michael Kunis married ballerina Alexandra Blacker in St. Petersburg, Fla., and the Hollywood stars were in attendance to watch the happy couple tie the knot at the Cathedral Church of Saint Peter. The wedding was followed by a reception at the St. Petersburg Yacht Club.
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Kunis and Kutcher also reportedly paid for the newlyweds' honeymoon in Australia as a wedding present.
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Michael met Blacker while she was training Kunis for her role as a ballet star in the Oscar-winning drama. They became engaged last year.
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The love match wasn't the only marriage to come from the film -- Kunis' co-star Natalie Portman wed choreographer Benjamin Millepied after meeting him on set.