2011 is surely shaping up as the year of the sibling. It's as if every celebrity in town shook their family tree and raining down like leaves came a new generation of matinee idols and starlets. Beyonce has Solange, James Franco has Dave, and Princess Kate has Pippa. Now, Conde Nast's two biggest lady's fashion mags--W and Vogue--are featuring pairings on recent covers. For Vogue's special-edition "Best Dressed" issue, Mary-Kate and Ashley Olsen gaze out blankly from the cover with their doe-eyes. On W, it's the Fanning sisters, Dakota and Elle, who play etheral partners-in-crime. Let's play a quick game of Sophie's Choice, shall we? Were you forced to pick one pair to save and one to perish, which would you rescue?