Free Twins: And What They Tell Us About Who We Are by Lawrence Wright Page B

surprising that the U.S. Central Intelligence Agency has performed experiments to determine whether twins have a significant ability to transmit knowledge telepathically. Twin lore is replete with anecdotes suggesting that illness or trauma in one of a pair of identical twins could be sensed by the other twin, even when they are far apart and unaware of the other's status. The unnamed CIA experimenters noticed that the brain's alpha rhythms can be elicited simply by closing one's eyes in a lighted room. They placed identical twins in separate rooms twenty feet apart and told them to open or close their eyes only on demand. Their brain patterns were carefully monitored. The experimenters theorized that eye closure in one twin should trigger alpha rhythms in both. Out of thirteen sets of

 

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twins, two sets produced the results that the CIA was looking for. None of the unrelated subjects involved as controls in the test showed any telepathic connection. "Extrasensory induction of brain waves exists between individuals when they are completely separated. It certainly is not a universal trait in all identical twins," the experimenters concluded. "Because of the paucity of controlled data, contrasted with the voluminous pseudoscientific and highly emotional information available in the realm of extrasensory perception, it appears unwise to draw any conclusions or to make any statements regarding these aspects of the current investigations." This provocative finding suggests that there is at least some basis for believing the stories twins so often tell about their telepathic awareness of each other when they are apart.
Twins also share genetic traits that do not run in families: they are idiosyncratic features that seem to be exclusive to identical twins. "Behavior geneticists have been talking for years about polygenic traits, like stature and IQ, that are determined by multiple genes in different locations on the genome, working together in an additive way," Lykken says. "But some traits may be determined by configurations of genes. For example, musical talent runs in families but singing ability does not." A singer requires talent, proper vocal apparatus, a musical ear, and perhaps certain features of personality that would encourage public displays. Each of these traits is partly genetically determined, which is why identical twins have such remarkably similar voices, but ordinary siblings seldom have voices that are really alike. Beauty, Lykken proposes, is another example of the configuration of various genetic traits that are not remarkable by themselves; traits of leadership and scientific genius may be as well. Perhaps the idiosyncrasies, the weird co-

 

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incidences, and the similarity of life events can be explained by the fact that identical twins are not just the sum of their individual genes but the product of many genetic constellations, which in a powerful, synergistic manner determine behavior, mannerisms, tics, social attitudes, marital relations, clothing choices, and political affiliations. Identical twins, in some respects, can be even more alike than we knew.
The mountain of data compiled by the Minnesota team, along with ongoing twins research in Boulder, Stockholm, and Helsinki, stunningly tipped the balance in the nature-versus-nurture debate. Bouchard and his collaborators assessed a variety of personality characteristics, such as a sense of well-being, social dominance, alienation, aggression, and achievement, which they described in an important article in the 1988 Journal of Personality and Social Psychology . On the question of IQ, the Minnesota team found a higher correlation for separated MZ twins than most previous twin studies: 0.76, almost exactly the figure that Cyril Burt stood accused of fabricating. Identical twins reared together score 0.86, as much alike as the same person tested twice (0.87). In the personality domain, the Minnesota team attributed about half of the