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  As for Bouchard’s twins being an unrepresentative sample because they were publicity prone, it is hard to imagine any twins, seeing the Jim twins chatting with Johnny Carson, assuming that they too would be ushered to The Tonight Show guest seats if they enlisted in Bouchard’s study. It is also hard to imagine twins shying away from the study because they felt they lacked Tonight Show–caliber sameness. This analysis ignores the powerful emotions that reunited twins all felt and suggests that their feelings gave way to a desire for publicity.

  Bouchard estimates that about 5 percent of the twins he examined had an appetite for publicity. Repeatedly it was demonstrated that the twins’ motives in participating was their interest in each other; all other considerations were minor in comparison. In addition, it was never demonstrated that an alleged interest in publicity would affect test results. Of even greater scientific weight than such ad hoc answers to ad hoc criticisms, most of Bouchard’s findings were later replicated by a Swedish study that recruited its subjects in a totally different way, one that did not in any way involve publicity.

  A matter of equal indifference to Bouchard’s twins, it turned out, was the hope of helping tip the nature-nurture debate in the direction of nature. Aside from the twins who were ignorant of the study’s objectives, most were oblivious to the genes-environment controversy to begin with and showed little interest in it during their stays in Minneapolis.

  For the majority of the twins who volunteered for Bouchard’s study, the primary motive for participation was an all-expenses-paid week of togetherness. Once reunited, twins invariably wanted to spend as much time together as possible. Two elderly Scottish ladies were among several sets who ended up living together. Understandably, in the first days after reuniting, twins were obsessed with becoming acquainted, of making up for lost time. In most cases, however, this was not easy. They often lived in different cities, sometimes different countries, they all had the usual entanglements of jobs and families, and meetings could be beyond budgets.

  The ages of Bouchard’s twins at their first reunion varied widely, but the mean age was thirty. Somewhat greedily, he included twins who were not separated immediately after birth, although the average age at separation was five months. Nor did he exclude twin sets who, although raised separately, had had occasional contact during their formative years. When the critics learned of this relatively rare exception to the twins’ reared-apart purity, they pounced and declared it a crippling flaw, a wipe-out contamination of the study’s claims of separateness. The reasoning seems to have been that with a pair of twins living apart, one Christmas dinner together could bring such traits as I.Q. and cardiovascular rhythms closer together.

  WHEN BOUCHARD’S TWIN-PROCESSING operation was in full swing, he amassed a staff of eighteen—psychologists, psychiatrists, ophthalmologists, cardiologists, pathologists, geneticists, even dentists. Several of his collaborators were highly distinguished: David Lykken was a widely recognized expert on personality, and Auke Tellegen, a Dutch psychologist on the Minnesota faculty, was an expert on personality measuring.

  In scheduling his twin-evaluations, Bouchard tried limiting the testing to one pair of twins at a time so that he and his colleagues could devote the entire week—with a grueling fifty hours of tests—to two genetically identical individuals. Because it is not a simple matter to determine zygosity—that is, whether twins are identical or fraternal—this was always the first item of business. It was done primarily by comparing blood samples, fingerprint ridge counts, electrocardiograms, and brain waves. As much background information as possible was collected from oral histories and, when possible, from interviews with relatives and spouses. I.Q. was tested with three different instruments: the Wechsler Adult Intelligence Scale, a Raven, Mill-Hill composite test, and the first principal components of two multiple abilities batteries. The Minnesota team also administered four personality inventories (lengthy questionnaires aimed at characterizing and measuring personality traits) and three tests of occupational interests.

  In all the many personality facets so laboriously measured, the Minnesota team was looking for degrees of concordance and degrees of difference between the separated twins. If there was no connection between the mean scores of all twins sets on a series of related tests—I.Q. tests, for instance—the concordance figure would be zero percent. If the scores of every twin matched his or her twin exactly, the concordance figure would be 100 percent. Statistically, any concordance above 30 percent was considered significant, or rather indicated the presence of some degree of genetic influence.

  As the week of testing progressed, the twins were wired with electrodes, X-rayed, run on treadmills, hooked up for twenty-four hours with monitoring devices. They were videotaped and a series of questionnaires and interviews elicited their family backgrounds, educations, sexual histories, major life events, and they were assessed for psychiatric problems such as phobias and anxieties.

  An effort was made to avoid adding questions to the tests once the program was under way because that meant tampering with someone else’s test; it also would necessitate returning to the twins already tested with more questions. But the researchers were tempted. In interviews, a few traits not on the tests appeared similar in enough twin pairs to raise suspicions of a genetic component. One of these was religiosity. The twins might follow different faiths, but if one was religious, his or her twin more often than not was religious as well. Conversely, when one was a nonbeliever, the other generally was too. Because this discovery was considered too intriguing to pass by, an entire additional test was added, an existing instrument that included questions relating to spiritual beliefs.

  Bouchard would later insist that while he and his colleagues had fully expected to find traits with a high degree of heritability, they also expected to find traits that had no genetic component. He was certain, he says, that they would find some traits that proved to be purely environmental. They were astonished when they did not. While the degree of heritability varied widely—from the low thirties to the high seventies—every trait they measured showed at least some degree of genetic influence. Many showed a lot.

  For the most part, the twins accepted the rigorous routine in good spirits, but occasionally one rebelled at the grueling pace. Returning from a hurried lunch to an I.Q. test, an elderly Australian lady complained angrily that she had not been given time to finish her coffee. Then, confronting a particularly tricky spatial-relations puzzler, the woman threw down her pencil and refused to proceed, snapping, “I can’t do this bullshit.”

  When told of the outburst during a staff meeting Bouchard let me attend, he turned to me and whispered, “It’s not like working with white mice.”

  By the end of the first year, Bouchard had examined twelve pairs of reared-apart identical twins and more pairs continued to come forward. Looking back on this period he says, “I got greedy very fast. By the end of 1980 I had twenty-one pairs, by the summer of 1981, thirty-nine pairs. That was the summer I busted my butt testing twins.”

  AS THOSE INITIAL MONTHS of recruiting and studying twins spread out into one year, then two, no papers on results were forthcoming, but many stories reached the press about bizarre similarities. The Jim twins were by no means the only ones with newsworthy parallels. Boggled by the unexpected discoveries, Bouchard and his staff could not remain silent about them. While understandable, this turned out to be a strategic mistake with lingering repercussions. The defenders of environmentalism, aware the Minnesota project had a strong potential for demolishing their belief systems, were alert for a means of discrediting it. The publicity about the weird twin “coincidences” provided one.

  Most of the planet’s five to six billion inhabitants are quite different—recognizably different to everyone who knows them. To have two individuals violate this fundamental fact of nature becomes the genetic equivalent of two women wearing the same dress to a party—titillating and slightly embarrassing, the stuff of giggles. As the bizarre similarities of Bouc
hard’s twins leaked out, derisive comments began appearing in the scientific press. Because no information was released about the meticulous testing, the study’s core effort, outside observers knew only about the gee-whiz oddities that, lacking context, cast a pall of bogus science over the project. A report of two sisters arriving in Minneapolis wearing seven rings each became an easy-to-ridicule whopper.

  A young scientist named Arlen Price, who began his academic career as a psychologist and eventually became a prominent behavioral geneticist, was following the Minnesota study with friendly interest. Not only did he read all the press reports, he would get periodic updates from a friend on Bouchard’s staff, Nancy Segal, with whom he had attended graduate school. As time went by and the amazing stories continued to appear in the press, Price telephoned Segal and urged her to persuade her colleagues to publish their substantive findings in scientific journals as soon as possible. Too much bizarre anecdotal stuff was appearing in the newspapers, he felt, and it was damaging the twin study’s credibility. He reminded them of a starchy saying in their profession: The plural of anecdote is not data.

  Segal replied that they could not publish until they had sufficient data for scientific conclusions; this took time. In that case, Price advised they should plug the leaks about the twin oddities. Segal assured him they were all aware of the problem.

  WHILE THE SENSATIONAL Minnesota anecdotes posed a threat to the overall study, developments elsewhere in the field of psychology were enhancing the timeliness and significance of a comprehensive separated-twins study. Before the findings from the Minnesota research are examined, a brief rundown of the new trends will provide relevant context. The most important developments were two new ideas about the environment that had emerged and that were complicating the tidy nature-nurture dichotomy. These were not mere refinements on the environment concept; they were major alterations that cast doubt on all previous attempts to sort out environmental from genetic effects.

  For most of the century, a rearing environment was regarded as a relatively fixed and stable entity, the setting in which the child and his siblings grew up. In addition, the environment was seen as an influence on a child’s development that was separate and distinct from innate influences—nature here, nurture over there. In analyzing the determinants of personality development, psychologists examined the environment as one phenomenon, generally the family home for young children, and, more recently, considered as well the genetic inheritance. They were seen as two diverse forces operating on each child. While adding genes to the equation was a sizable advance over the years of ignoring them altogether, renovations on the paradigm were by no means completed.

  Psychologists, even those who acknowledged genetic influences, were bothered by a fundamental question. If environment was so powerful in determining personality and behavior, why were there such enormous differences between brothers and sisters who had been raised in the same homes and who shared roughly 50 percent of their genes? To answer this question, Sandra Scarr and her colleagues at the University of Virginia and Robert Plomin and others at Pennsylvania State University developed the concept of nonshared environment, that is, the environment particular to each child in a family. This might be a special relationship with a parent, special treatment to the last born, and so on. It could also include varying biological conditions in the womb or in early nurture. Later in development it could be different friends, perhaps different schools.

  When studies were run to examine this idea, it was found that the nonshared environment played a much bigger role than the shared one. In fact, the shared environment, the one previously assumed to be the only environment, turned out to have a negligible effect on personality development. Brothers and sisters were rarely much alike, and, to the degree that they were, the similarities were found to be genetic, not environmental.

  The other major new conceptual shift was that the fundamental environment children start with may not be free of genetic influence. Previously it was thought that if a child grew up in a family of animal lovers, surrounded by pets, that milieu was considered environment, plain and simple. As such, it would be cited as the explanation for the child’s fondness for animals. With the broadening genetic perspective, however, the houseful of pets might be seen as a manifestation, at least in part, of the parents’ genes, elements in the parents’ fundamental nature that distinguished them from others. And if the parents’ love of animals had a genetic basis, these genes could well be shared to a degree by the offspring. Pets and genes were hopelessly mixed. And while the traditional psychological view had been that the pets were a molding environmental influence, it now turned out that the pets and the child’s love of pets might both be expressions of genes shared by parent and child.

  Ethologists had long known that many organisms go a long way toward creating their own environment—everything from earthworms producing the soil they move through to beavers living in lakes they themselves created. Their environments were seen by some ethologists as functions of their genetic makeup—or to use Richard Dawkins’s phrase, such self-made environments were manifestations of “the extended phenotype.” According to this concept, the line between an organism and its environment grows indistinct. To Dawkins, the beavers’ dams were extended manifestations of their genes. Carried further, this idea would suggest that an individual’s hobby, career, and marriage might be seen as extensions of his or her genotype. They would be colored and shaped by the environment, to be sure, as hair color and skin texture are, but manifestations of genes all the same.

  An example of molding one’s environment could even be seen in a child of a few months, one young enough for the environment to have little opportunity to twist and form. Except for those that cling to the blank-slate notion, most would agree that an infant, in the first months after birth, is pretty much a raw genetic package. If genes produced a fussy, irritable baby boy, he would confront very different parents than his well-behaved brothers and sisters. He would have made his environment different than theirs. In school, the hyperactive, inattentive child will find himself facing a hectoring, hostile teacher who is nice as pie to the child’s model classmates. Carrying this mechanism to an extreme, the most problematic, troublemaking child may, as he grows, find himself in a special school, a reformatory, or a juvenile prison, in which case he will have succeeded in changing his environment totally.

  These new ideas were major changes in the neat nature-nurture model and went a long way in discrediting the numerous studies that for years had examined and measured the environment in order to appraise the external effects on developing children. Genes and environment were now recognized to be deeply entwined. Each child was seen as having a unique genetic makeup and a unique environment as well, a portion of which was determined by the child’s genes.

  This was true of all children—except identical twins, for whom the environments varied but the genes were the same. Even though the rearing settings of separated twins might have been similar—as the critics, in some desperation, never tired of pointing out—the environments were all by definition different to some degree, certainly more different than the one-home environment of reared-together twins. And they would also be experiencing at least as much variation of non-shared environment as reared-together twins, probably a lot more. For these reasons, and taking into account the revised view of environment, reared-apart identical twins still provided the best conceivable study subjects for sorting out genetic from environmental effects.

  Other developments made the time propitious for a definitive reared-apart twin study. Not only Wilson’s Sociobiology but a number of other intellectual developments were leading to a growing receptivity to genetic-biological influences on human behavior and a concurrent (but often independent) weakening of the longtime conviction about the environment’s overriding power to mold children. These shifts in enlightened thinking were the culmination of currents stirring in the scientific world for nearly a century and will be explored in chapt
ers 12 and 13. After periods of exile, the biological approach to behavior was reasserting itself in the late 1970s and set the stage for the definitive research project Bouchard was undertaking.

  FOUR

  COSMIC SECRETS OF TWINS

  TO FUND THE TWIN STUDY, Bouchard had continued to receive grants from his own university; from an original backer, the Spencer Foundation; and from the National Science Foundation. These sources were limited, however, and his need for money was always pressing. Bringing twins to Minneapolis from different parts of the world and housing them for a week cost more than feeding colonies of fruit flies.

  An early source of support was the Pioneer Foundation, a New York–based charitable trust established in 1937 by a textile millionaire, Wickcliffe Draper, to fund research that would “improve the character of the American people.” A strong obstacle to this goal, in Draper’s view, was mixing the races, and this unsavory slant came to the public’s attention when the foundation helped fund the genetic research of William Shockley, the Nobel Prize winner with openly racist views.

  Bouchard is unapologetic about accepting money from Pioneer. “They give grants for controversial stuff like twin studies and behavioral-genetic studies,” he said. “They fund stuff on race. They also fund Phil Rushton, a very controversial character who does work on race differences. They’ve been accused of all kinds of things, being racist and so on. I don’t think it’s justified, but I couldn’t care less. My rule is that if they don’t make any restrictions on me—what I think, what I write, what I do, I’ll accept their money. I submit my grant proposals to them, the proposals are reviewed, the Pioneer people choose to fund them. Why do they choose to? That’s their business. Then I’m free to do whatever I want. I don’t care who they are.”