Do not keep them separated, expert says
Studies highlight the importance of keeping twins together when adopted
Studies of reared-apart twins have shown that in general, half the differences in personality and religiosity are genetically determined, but for a trait like IQ, about 75 per cent of the variation, on an average, is genetic, with only 25 per cent influenced by the environment.
Studies of heart disease in twins have shown that genes confer a potential, but the environment often determines whether that potential is expressed. For example, perfect pitch tends to run in families and may even be tied to a single gene, but without early musical training, the trait is unlikely to be expressed.
In the documentary Three Identical Strangers, the triplets separated at birth revealed differences in their susceptibility to mental illness, with the one who was reared by an authoritarian father more seriously affected than the two with warmer, more nurturing parents.
Relative contributions
Decades-long studies of identical and fraternal twins — and in some cases, triplets — who had been separated at an early age and reared in what were often strikingly different environments have documented the important interaction of nature and nurture and help to explain the relative contributions of each to how a child develops.
Nancy Segal, a psychologist at California State University, Fullerton, and herself a fraternal twin who has made a career of twin studies, starting with the Minnesota Twin Family Study, is the author of Born Together — Reared Apart: The Landmark Minnesota Twins Study, published in 2012. She has also written Twin Misconceptions: False Beliefs, Fables and Facts About Twins. She said the studies highlight the importance of keeping twins, especially identical twins, together when adopted.
Segal said: “The triplets deeply resented having been separated. They lost out on wonderful years they could have had together. There was an immediate bond, an understanding of one another, that was obvious as soon as they found each other.”
Sudies of heart disease in twins have shown that genes confer a potential, but the environment often determines whether that potential is expressed.