About four years ago, Kevin Sinclair inherited an army of clones. Very fluffy clones. "Daisy, Debbie, Denise and Diana," says Sinclair, a developmental biologist at the University of Nottingham in England. The sheep are just four of 13 clones that Sinclair shepherds, but they're the most famous because of their relation to Dolly, the sheep that made headlines two decades ago as the first successfully cloned mammal. " 'Sister clones' probably best describes them," Sinclair says. "They actually come from the exactly the same batch of cells that Dolly came from." Recently, Sinclair and his colleagues celebrated the sister clones'...