How can identical twins be genetically different?

They sleep together, eat together, and most people find it impossible to tell them apart. Identical twins who grow up together share just about everything, including their genes. But sometimes only one twin will have health problems when genetics predicts both of them should.

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<p><a href="http://www.physorg.com/news73070448.html">How can identical twins be genetically different?</a></p> <p>They sleep together, eat together, and most people find it impossible to tell them apart. Identical twins who grow up together share just about everything, including their genes. But sometimes only one twin will have health problems when genetics predicts both of them should.</p>