Studies (Plomin and Daniels) have concluded that siblings have no more in common in their personalities than two completely unrelated strangers. Your observations appear to be correct—even if 50 percent of your genetic code is the same—for your family. The five siblings will be different. Researchers have found that the differences do not lie in the genetic code, but in the environment in which siblings grow up. “But we all live together in the same house,” you say. That may be true in the sense that you reside in the same living quarters. The answer to this conundrum appears to be that each child actually grows up in a different environment. More tomorrow.