study twins who were separated at birth and reared in different families. He found that an identical twin reared away from his or her co-twin seems to have about an equal chance of being similar to the co-twin in terms of personality, interests, and attitudes as one who has been reared with his or her co-twin.
[3] Bouchard has said that these two twins happened to be unusually alike, while most twins show more differences:
"There probably are genetic influences on almost all facets of human behavior, but the emphasis on the idiosyncratic characteristics is misleading. On average, identical twins raised separately are about 50 percent similar -- and that defeats the widespread belief that identical twins are carbon copies. Obviously, they are not. Each is a unique individual in his or her own right."