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Mmm. Smells just like your identical twin. iStockphoto hide caption

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NPR intern Poncie Rutsch takes a crack at making a big sound. Meredith Rizzo/NPR hide caption

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Kevin Lopez at home in Greenbelt, Md. Meredith Rizzo/NPR hide caption

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Will this maker of snus, an alternative to cigarettes, be allowed to claim it is less harmful? Swedish Match hide caption

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Brazilian mothers participate in a demonstration in 2011 for the right to breastfeed in public, in Sao Paulo, Brazil. Eduardo Anizelli/STF/LatinContent/Getty Images hide caption

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Along with sperm, the in vitro procedure adds fresh mitochondria extracted from less mature cells in the same woman's ovaries. The hope is to revitalize older eggs with these extra "batteries." But the FDA still wants proof that the technique works and is safe. Chris Nickels for NPR hide caption

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