When Two Are Like One
Identical twins don’t make obvious evolutionary sense; fraternal twins at least have the benefit of genetic diversity, improving the odds that at least one might survive whatever misfortune comes their way. And yet, in their utter inexplicability, identical twins have helped elucidate our most basic understanding of why, and how, we become who we are. By studying the overlap of traits in fraternal twins (who share, on average, 50 percent of their genes) and the overlap of those traits in identical twins (who share 100 percent of their genes), scientists have, for more than a century, been trying to tease out how much variation within a population can be attributed to heredity and how much to environment. ‘‘Twins have a special claim upon our attention,’’ wrote Sir Francis Galton, a British scientist who in the late 19th century was the first to compare twins who looked very much alike with those who did not (although science had not yet distinguished between identical and fraternal pairs). ‘‘It is, that their history affords means of distinguishing between the effects of tendencies received at birth, and those that were imposed by the special circumstances of their after lives.’’
Galton, who was Darwin’s cousin, is at least as well known for coining the term ‘‘eugenics’’ as he is for his innovative analysis of twins (having concluded, partly from his research, that healthy, intelligent people should be given incentives to breed more). His scientific successor, Hermann Werner Siemens, a German dermatologist, in the early 1920s conducted the first studies of twins that bear remarkable similarity to those still conducted today. But he also drew conclusions that for decades contaminated the strain of research he pioneered; he supported Hitler’s arguments in favor of ‘‘racial hygiene.’’ In seeking genetic origins for various traits they considered desirable or undesirable, these researchers seemed to be treading dangerously close to the pursuit of a master race.
‘So we were swapped,’ Wilber said, shrugging. ‘You’re my brother, and you’ll be my brother until the day I die.’
Despite periods of controversy, twins studies proliferated. Over the last 50 years, some 17,000 traits have been studied, according to a meta-analysis led by Tinca Polderman, a Dutch researcher, and Beben Benyamin, an Australian, and published this year in the journal Nature Genetics. Researchers have claimed to divine a genetic influence in such varied traits as gun ownership, voting preferences, homosexuality, job satisfaction, coffee consumption, rule enforcement and insomnia. Virtually wherever researchers have looked, they have found that identical twins’ test results are more similar than those of fraternal twins. The studies point to the influence of genes on almost every aspect of our being (a conclusion so sweeping that it indicates, to some scientists, only that the methodology must be fatally flawed). ‘‘Everything is heritable,’’ says Eric Turkheimer, a behavioral geneticist at the University of Virginia. ‘‘The more genetically related a pair of people are, the more similar they are on any other outcome of interest’’ — whether it be personality, TV watching or political leaning. ‘‘But this can be true without there being some kind of specific mechanism that is driving it, some version of a Huntington’s-disease gene. It is based on the complex combined effects of an unaccountable number of genes.’’
Arguably the most intriguing branch of twins research involves a small and unusual class of research subjects: identical twins who were reared apart. Thomas Bouchard Jr., a psychologist at the University of Minnesota, began studying them in 1979, when he first learned of Jim and Jim, two Ohio men reunited that year at age 39. They not only looked remarkably similar, but had also vacationed on the same Florida beach, married women with the same first name, divorced those women and married second wives who also shared the same name, smoked the same brand of cigarette and built miniature furniture for fun. Similar in personality as well as in vocal intonation, they seemed to have been wholly formed from conception, impervious to the effects of parenting, siblings or geography. Bouchard went on to research more than 80 identical-twin pairs reared apart, comparing them with identical twins reared together, fraternal twins reared together and fraternal twins reared apart. He found that in almost every instance, the identical twins, whether reared together or reared apart, were more similar to each other than their fraternal counterparts were for traits like personality and, more controversial, intelligence. One unexpected finding in his research suggested that the effect of a pair’s shared environment — say, their parents .had little bearing on personality. Genes and unique experiences — a semester abroad, an important friend — were more influential.
As pure science, the study of twins reared apart has troubled some researchers. Those twins either self-select and step forward or become known to researchers through media reports — which are less inclined to cover identical twins who do not look remarkably alike, who did not marry and divorce women of the same name or choose the same obscure hobby. Identical twins who do not look remarkably alike, of course, are also less likely to be spotted and reunited in the first place. And few studies of twins, whether reared apart or reared together, have included twins from extremely different backgrounds.
‘‘Every study will have its critics,’’ says Nancy Segal, a professor at California State University, Fullerton, who worked with Bouchard from 1982 to 1991. ‘‘But studying twins reared apart separates genetic and environmental effects on behavior better than any research design I know.’’
Segal has been studying Chinese twins (fraternal and identical pairs reared together and reared apart) since 2003. In several books about twins, Segal has merged science with human-interest tales, walking readers through statistical evidence but also highlighting anecdotal details: the identical twins reared apart who each showed up for research wearing seven rings, or the reared-apart sisters who rubbed their noses the same way and called it ‘‘squidging.’’
Last October, Yesika Montoya, a Colombian psychologist who is now a social worker at Columbia University, saw on Facebook a video clip from a Colombian newsmagazine program, Séptimo Día, which confirmed through DNA testing that the four young men were two sets of identical twins. She got in touch with Segal, whom she knew only by reputation. She then approached the young men, who agreed to be the subject of their research.
No matter how fascinating, the two sets of twins represent a sample of only two. But to Segal, the possibilities were dizzying, unique. In no other family she knew of were there so many kinds of twin pairings to analyze and compare: Jorge and Carlos, Jorge and William, Jorge and Wilber and so on. ‘‘It’s an experiment within an experiment,’’ she said, comparing it to one of those Russian dolls: Crack open one, and there would still be another, and another, and another.
The twins knew the research would require them to submit, over the course of a week in March, to several probing interviews, individually and in pairs, as well as hours holed up in a conference room filling out questionnaires. There would be questions about their homes, lives and education, as well as personality and intelligence tests. Segal told them that she was interested in writing a book about them (Montoya would later collaborate with her), and the young men were enthusiastic subjects.
William had only one condition for his participation: He insisted that Segal and Montoya visit the home in which he grew up in Santander. Without that, he thought, they could never really understand who he was. He did worry, however, that if he told Segal and Montoya how long it would take to get to Santander, they would never agree to go. So he dodged and evaded whenever the subject of travel time came up. It’s a four- or five-hour drive, William would say, and then add, almost as an afterthought, that when the road could get them no closer to their destination, they would get out and walk. For how long? A little while, William would say; it might be a little muddy. How muddy? Maybe, he would suggest, it would be easier if at that point Segal traveled by horse. Would she, by any chance, rather ride a horse? Segal, a woman in her early 60s who grew up in the Bronx, said no.
The Importance of Will
Around 9:30 a.m. on March 29, three cars pulled into La Paz, a dusty town whose few small streets offer sweeping views of the Andes. The group — Segal, Montoya, the two sets of twins, translators and assorted friends and family members — had already been on the road for six hours. They settled in for a traditional breakfast of bone broth and hot chocolate at a diner in town. Jorge and William sat next to each other along one side of a wooden table, while Carlos sat across the way. Wilber sat with Segal and Montoya. While everyone ate breakfast, Carlos took out his phone and called up a picture of him and Jorge. ‘‘I love my brother, even though I only show it when I’m drunk,’’ Carlos said. ‘‘See?’’ In the picture, Carlos was puckered up, giving Jorge a big kiss on the cheek.
William watched Carlos, feeling annoyed. Wilber, he had often thought, was the same way: He took William entirely for granted, showing his love only on very rare occasions — when, for example, he thought one of them could die. They served in the same platoon in the military, and when they entered a particularly dangerous zone, Wilber would say to him, white-faced: ‘‘May God be with you, my brother. I love you.’’ William knew Wilber loved him; but both Jorge and William wished that the brothers they grew up with had been more supportive, more expressive — the way William and Jorge now were with each other. They often called each other right before they fell asleep, just to say good night.
The four young men all knew one another well by then. Over the past six months, they had gone on outings and shared meals, talked about women, family, money, values. Even weeks in, each had stared, still unnerved and amazed, into the eyes of his identical brother. They had measured, assessed and inspected. They stood back to back, comparing height (those raised in the city were taller than those from the country); Carlos had crushed Wilber in a food-eating contest, William had vanquished them all when they arm-wrestled. In the stands at a soccer match, Carlos watched, in fascination, as William’s hand reached down his jeans to scratch his backside: Jorge did the same thing, Carlos told Wilber. Over dinner one night, Jorge noted that Carlos and Wilber both leaned in at the same odd angle toward their plates. Jorge felt comfortable gently correcting his identical twin’s grammar; Carlos took seriously such brotherly responsibilities as instructing Wilber in how to approach an attractive Bogotá woman at a bar or how to down a shot of tequila. The twins from Santander were amazed that neither of their city counterparts had ever fired a gun, which they quickly remedied on a visit to the country.
Carlos did feel immediately at ease with his newfound twin, he had to admit. Wilber did not try to tell him what to do when he talked about his love life, the way Jorge did; he just listened and supported him. Yes, they understood each other: their manly pride around women, their furious response to their brothers’ incessant teasing. But Carlos was also unnerved by Wilber’s Carlosness. His twin’s very existence refuted a concept dear to him: his sense of his own uniqueness. Having grown up so different from his other family members, he had come to pride himself on his individualism; now, as an identical twin, he was part of a rare subset of humans whose replicability was embarrassingly on display. Once, Wilber posted on Facebook a picture of himself back in Santander, bare-chested in a river, triumphantly holding two chickens he had just killed. With his hair wet and slicked down like Carlos’s, the campesino in the picture looked too much like Carlos for his comfort. ‘‘Take that thing down,’’ he told Wilber. ‘‘People will think it’s me.’’
Far from believing that he had found his perfect other half, Carlos felt lonelier than ever. For all of Jorge’s reassurances, he could feel Jorge drifting toward William. The two now wore the same sneakers, shaved their goatees the same way. On weekends, Jorge often went to William’s butcher shop and got behind the counter, waiting on customers, so he could spend time with his twin. He sometimes slept at Wilber and William’s tiny apartment, while Carlos slept at home. Sometimes Carlos told himself, with a strange twisted relief, that he was glad this had all happened after his mother died; the jealousy he would have felt had she embraced William as Jorge had would have been more than he could take.
Carlos knew that Jorge was attuned to his sadness, that he even wanted to help. But whenever they tried to talk about it, they fell into mutually irritating old patterns. Carlos felt as though Jorge dismissed his concerns; Jorge felt frustrated that nothing he said could assuage Carlos’s sense of isolation. But Jorge tried. Six weeks or so after the reunion, Jorge asked Carlos for a photo of himself. That Saturday, Jorge went to a tattoo parlor. He already had a tattoo of his mother over his heart. Now he sat in a chair for four painful hours as his favorite practitioner needled his brother’s image permanently into his flesh, just inches away from the image of his mother. He came home and lifted his shirt to show Carlos the work, his skin still bloody and swollen from the violence of the needle. It was, Carlos would later remark, with tears in his eyes, the best present anyone had ever given him. It brought him some measure of peace.
At breakfast in La Paz, however, Carlos felt that Jorge was provoking him once again. Moments after Carlos pulled out that photo, Jorge turned to him and brought up a sensitive subject the two had already discussed in many late-night conversations: Who would Carlos have turned out to be had he been raised in Santander?
Come on, Carlos, Jorge said — look around. Do you really think that if you had been raised here you would have ended up an accountant or even a professional?
Carlos refused to concede Jorge’s point. Who was to say he wouldn’t have found a way to go to school, to get his degree, to be working in the very same firm where he had only just recently been promoted?
William said nothing, but his face took on a hard cast. Carlos had no idea, he thought, how far a strong will could or could not get you. William had that strong will, had tried to exert it in every way, desperate to get to that petty-officer training. First, he had moved to Bogotá to study for his high-school degree. He managed to pass the test, but his score was low — eight months of part-time cramming could not make up for all those years of lost schooling. He made it only onto a waiting list for the petty-officer training, but that did not deter him. He packed up, left Bogotá and took a long bus ride to the barracks where the leadership course was being offered. When William arrived at the barracks, a commanding officer recognized him. ‘‘Those who persevere succeed,’’ the officer told him. The commanding officer managed to pull some strings on William’s behalf, but as they were going through the paperwork, officials discovered that William had already been discharged and compensated by the military for a disease he contracted while serving. The compensation made him ineligible for re-enlistment. There were no more strings to be pulled; he could never be a petty officer; it was over. He would have to go home. But hadn’t the commanding officer told him that those who persevere succeed? For five days, William stayed past his welcome, hiding and mingling among the groups of soldiers. He hoped that things would sort themselves out, but more than that, he could not bring himself to leave: Leaving meant he had given up. On the sixth day, a sympathetic but fully armed officer accompanied him to the bus station and personally put him on a bus back to Bogotá.
William knew that Carlos was unfamiliar with that part of his history. Carlos probably did not know that William, as a 6-year-old, used to walk with his mother to this very town, La Paz, for five hours each way, just to buy groceries; they would spend the night at a kind woman’s place in town and then walk home again, groceries on their backs. And Carlos could not know, could never really know, how many hours William had spent hacking sugar cane with a machete as a teenager, his skin crawling from the heat and the itchy scraps of stalk, carrying 50 pounds of cane at a time, mindless, painful, strenuous work. Carlos had spent those same years, William knew, flirting with girls at an excellent public high school, playing basketball with his friends, racking up points on some video game, the name of which William would not even know.
Carlos was wrong, William felt certain. Sometimes, a will was not enough. Had he grown up in Santander, Carlos would not be an accountant on the rise right now. And Carlos’s insistence on that point felt, to William, like an insult to all he had endured — a life he had endured, no less, in Carlos’s place.
When City Meets Country
After breakfast, the cars left La Paz, driving on serpentine, stone-strewn roads with lush palm fronds and ferns closing in overhead. With the heat of the sun now strong, one driver kept mopping his sweating face with a bandanna he borrowed from one of the relatives in the car, as if he was physically exhausted from the stress of maneuvering the vehicle over riverbeds and around ditches. Finally, around 11:30 a.m., the caravan stopped near a large gazebo in a grassy field. Everyone piled out of the vehicles. It was time to walk.
Segal had brought a bright purple rolling suitcase, which held materials she hoped to use that day for interviews and research with William and Wilber’s family; their brother, Ancelmo, now lived in their childhood home, but their parents and other relatives would also be there to celebrate Ancelmo’s birthday and see the twins. It became clear that the grassy path would not be suitable for luggage rolling, so William, who had carried far heavier loads on this journey before, easily slung the purple suitcase onto his shoulders
The group started making its way along the path, which briefly lurched uphill. William was moving at high speed, despite the suitcase. He called out that as strong as he was, Jorge was every bit as strong, although it seemed unlikely that that could possibly true. ‘‘But not Carlos,’’ William said. ‘‘Carlos is not as strong.’’ William took a few more steps, then turned around as if something had occurred to him. ‘‘Why shouldn’t Carlos carry it?’’ he said. He backtracked until he reached Carlos, pushed the suitcase at him and then quickly headed off.
The path tracked across a grassy meadow and then started a long, steep descent. Within minutes, the path was made of mud — rich, claylike mud that was two feet deep in some patches. Carlos, who was always impeccably dressed, stepped carefully. But his Adidas basketball sneakers were quickly soaked with oozing earth.
It was high noon in Santander. Carlos picked his way through the mud, which splattered and quickly baked hard onto his legs in the sun. Then Carlos — Carlos, who was so vain about his clothing, fussy about fit, who was always brushing at the cuff of his pants to rid it of some imaginary lint — let out a howl. His foot had sunk deep in the mud. Slowly, with the help of someone from the area who was walking alongside him, he began to extricate it. There was a loud suctioning sound: Sludge coated his bare leg well past his knee.
More than an hour later, sweaty, exhausted, filthy, Carlos arrived with the group at William and Wilber’s childhood home. It had no toilet, no drywall, no paint, just wooden sides and a wood-burning stove with a pipe jutting out of the roof. Carlos approached Carmelo with a smile: The two hugged warmly. But then there was silence; neither seemed to know what to say. William was standing close by, watching Carlos and his father. William looked pristine, except for a little mud on his boots. He wore a striped purple button-down shirt for the occasion; Carlos was dressed in a black baseball cap with a Batman symbol on it, a tank top and sunglasses. He had not even had a moment to catch his breath when William quickly batted his cap. ‘‘Take off your hat and sunglasses,’’ William told Carlos. ‘‘Try to really be here.’’
Carlos watched Jorge, who was moving easily through the crowd, ingratiating himself with William and Wilber’s family in a way that Carlos still could not. Carlos was still annoyed about the conversation they had at breakfast. Jorge seemed to want him to make some grand emotional statement about how lucky he had been in the swap, how much tougher his lot would have been had he, in fact, been raised in Santander. It was not as if he hadn’t thought hard, lying awake many nights, about what his fate would have been had he been raised with this biological family. Two of William and Wilber’s brothers had died very young, one in a gun accident and one in an ambush while serving in the military. He might not even be alive if he had grown up here. Maybe it was easy to be a good guy in Bogotá. Maybe if he had grown up in Santander, he would have joined the guerrillas, who were popular a decade earlier but also brutal. Far from believing in the inevitability of his professional success, he worried about whether his character, in that alternate life, would have withstood the forces around him.
But no, he was not going to say all of that at breakfast, in front of a bunch of people. That was not who he was.