ELEVEN
Paired and Pared
The Curious Worlds of Twins and Singletons
If you were an only child in the early 1920s, you’d have probably wanted to avoid G. Stanley Hall. A psychologist, a professor, and the first president of the American Psychological Association, Hall knew a thing or two about how the human mind works. Often thought of as America’s Sigmund Freud, he even bore a physical resemblance to the grand Austrian. When the two famously met at Hall’s Clark University in 1909, it was thought of as a historic moment for modern psychology, even if the picture it produced—of two somber bearded men glaring with matching humorlessness into the camera—was equal parts earnest and comic.
Hall’s severity was more than just appearances. Author of the 1883 book The Contents of Children’s Minds on Entering School, he had some very clear ideas about the worth of boys and girls—and none of it made for very happy reading. Childhood, he taught, was a time of near savagery, during which “normal children . . . pass through stages of passionate cruelty, laziness, lying and thievery.” During adolescence, “every step of the upward way is strewn with wreckage of body, mind and morals.” The bloom of full teenhood was not much better, with most children becoming “emotionally unstable and pathic.”
It was possible to tame and civilize such proto-people, provided you took a firm and unforgiving hand. Reasoning with children was useless, and had to be replaced with iron discipline; precociousness had to be snuffed in favor of strict pedagogy. Budding teen sexuality should be rechanneled into vigorous athletics. Failing to do so could lead to masturbation, which was a waste of sexual energy; sexuality, in turn, was a highway to debauchery.
But even such extreme measures could do little to save the luckless boy or girl born into the world without any brothers or sisters. Such solitary children were afflicted with all the shortcomings that beset other young people, but without the civilizing influence of siblings, the singleton traveled an even more perilous path. Pampered, narcissistic, socially inept, singletons would be destroyed by their childhoods before they ever reached maturity. “Being an only child,” Hall wrote, “is a disease in itself.”
Hall was hardly alone in his low opinion of the only child. Indeed, he was almost sunny compared to psychiatrist Abraham Arden Brill. Another of the Austrian giants, Brill studied with Jung, then emigrated to the United States, where he taught at New York University and Columbia and was the first to translate the works of Freud into English. In his 1921 book, Basic Principles of Psychoanalysis, Brill also addressed the sorry lot of the singleton, and wrote: “The only child is the morbid product of our present social economic system. He is usually an offspring of wealthy parents who, having been themselves brought up in luxury and anxious that their children should share their fate, refuse to have more than one or two children. By their abnormal love they not only unfit the child for life’s battle but prevent him from developing into normal manhood, thus producing sexual perverts and neurotics of all descriptions. It would be best for the individual as well as the race that there should be no only children.”
Over the arc of the past century, of course, Brill’s and Hall’s hard sentiments—like so much else of what we thought we knew about psychology—have been discredited. Generations of happy, thriving only children are proof that siblings are not the sine qua non to a happy life. But that doesn’t mean that parents and psychologists don’t worry over singletons all the same. The nurturing, socializing effect of siblings is a real and powerful thing, and it’s reasonable—indeed only logical—to assume that kids who lack sibs might wind up unnurtured and unsocialized. An entire childhood spent being tended by adoring parents who have no other outlet for their caretaking can produce an orchid of a child—a pampered, spoiled, hothoused thing, too temperamentally fragile to survive in the wilds of the world. Singletons will learn selfishness when they should learn sharing, inflexibility when they should learn compromise, narcissism when they should learn generosity.
Between 1925 and 1986 alone, there were more than 200 major papers published that sought to determine what type of damage is done to a child as a result of growing up alone. The findings were often mixed, with some studies unearthing no difference at all between singletons and kids with sibs and others darkly warning that there were dangers indeed. No matter which body of data was correct, the childbearing, familyraising public had already made up its mind.
A 1956 study found that one of the leading reasons couples chose to have a second child was not that they necessarily wanted a bigger family but that they wanted to spare their firstborn the burden of growing up alone. A 1974 study found that 78 percent of Americans believed that singletons are “disadvantaged.” Another study published that same year described only children as “generally maladjusted, self-centered and self-willed, attention-seeking and dependent on others, temperamental and anxious, generally unhappy and unlikeable.” Their only advantage? They are “somewhat more autonomous than a child with two siblings.”
But singletons, at last, are getting a break. With the passage of time come better methodology and less investigative bias, and the body of work conducted since the 1970s has turned up much more reliable—and generally much happier—results. It’s true that only children do not have the in-house playmates, roommates, mentors, and life mates that brothers and sisters have. And it’s true that in the broadest terms, having such influences is a very good thing. But it’s not equally true that not having them does any harm at all. Indeed, in one modern study after another, singletons show themselves capable of finding compensations, of filling the voids that would ordinarily be filled by siblings. As a result of that adaptability, not only do they usually perform as well as kids who have brothers and sisters on a range of social, intellectual, and cognitive scales, they often do better.
“Outcomes are more important than processes,” says psychologist Toni Falbo, professor of educational psychology at the University of Texas, Austin, and an expert on the psyches of singletons. “And the outcome is that these kids wind up with the same skills other children have. The question is, How does that happen? Somehow they get adequate experience.” Her work and that of others are increasingly solving that riddle.
For a demographic group that’s had to put up with such heat over the decades, singletons represent a surprisingly sizable portion of the population. There are currently about 20 million one-child households in the United States. Among single mothers—itself a significant demographic group—the share raising a single child has more than doubled in the past two decades, going from 10 percent in the late 1980s and early 1990s to 23 percent today. In the UK, about 17 percent of families are home to just a single child, and in trendsetting Manhattan—where apartments are tiny, both parents typically work, and the cost of living is stratospheric—the figure is a remarkable 30 percent.
Not all parents raising singletons planned in advance to have just one child, but a significant percentage of them do, and that share is slowly creeping up. According to a 1985 U.S. Census report, 12.7 percent of eighteen- to thirty-four-year-old women reported that they intended to bear a single child and stop after that. Today, that figure is 13.9 percent.
The size of the only-child population is partly determined by historical forces as well, and those can drive the figures both up and down. During times of war there is usually a bump in the number of singletons, often because a father is killed or disabled in combat after he has begun his family but before he has completed it. Singletons are often a knock-on effect of rising divorce rates, too, as parents split up after having just one child. Hard economic times similarly drive family size down and the singleton population up, with parents deciding that a larger brood is just not something they can support. The twenty-first-century United States—with two wars, a historically severe recession, and a divorce rate that fluctuates from 25 percent to over 50 percent, depending on the demographic group—is at the mercy of all those variables.
Whatever the factors are that lead to one-child families, there’s no denying that the children in those homes do live their lives as an object of parental attention in ways that multiple sibs never do. The time, money, and other forms of investment that must be so carefully husbanded when there are two, three, or more kids in the house are directed exclusively toward the one child. Sharing and turn taking—among the hardest of all skills for small children to learn and the most common causes of shoutfests and fights—is not a problem in the singleton’s home.
With more disposable income to spend, there are also more treats and privileges such as movies, vacations, summer camps, private schools, and high-price colleges. Singletons are likelier to enjoy educational and extracurricular goodies such as musical instruments, newer computers, dance lessons, and after-school sports, as well as tutors and trainers to help them make the most of it all. They are less likely to be pressed into household chores—in part because a one-child home simply needs less picking up than a multi-child one does. And without a lot of kids with different preferences and temperaments to accommodate, the singleton’s tastes are more often indulged.
“Think about how parents of multiple kids have to select foods for different meals to appeal to the appetites of one child and then the other,” says Daniel Shaw of the University of Pittsburgh. “With only one child to cook for, the parents will cater to that child’s tastes. The choice of family outings and other activities can similarly be determined by the desires of the singleton, as opposed to thinking about multiple children who vary in developmental skills and desires.”
Only children may even be healthier than other kids. The mere fact that parents have just one child’s schedule to juggle—and one set of pediatrician’s bills to pay—means that singletons are likely to see the doctor more regularly, and to return for follow-up visits after recovering from an illness or injury. (This happy fact of the singleton’s life may, paradoxically, have accounted for one of Hall’s most troubling and misinterpreted findings. Over the course of his career, Hall kept a detailed archive of all of the patients brought to him for care, paying special attention to what he called “exceptional and peculiar children.” There were more than 1,000 kids on that unfortunate list, and when he broke them down by family size he found that a disproportionately large number of them were singletons. That seemed to seal the deal against the only child, since Hall—this time at least—appeared to have hard numbers on his side. But a less grim—and more accurate—interpretation was simply that an only child going through a rough behavioral patch was likelier to be brought in for care than a child with brothers and sisters. Often as not, that difficult period would pass, just as it would for a child from a larger family who would never have gotten professional attention. But the singleton would have been permanently inked into Hall’s book all the same.)
Pampering, of course, is only one part of the singleton’s life; pressure is the other—and that’s a lot less easy to take. From fish to birds to mammals to humans, the reproductive calculation is always the same: More offspring are better than fewer, since that allows you to place your genetic bets on as wide a field as possible. When human parents are raising a house full of children, simple arithmetic says that at least some of them will grow up wealthy and successful and produce a lot of kids of their own. A single child, by contrast, means you’ve got just one horse in the race—and that horse must be a winner. Not only do parents feel that urgency, they make sure the child does as well. “There’s a pressure to achieve that constantly comes from the parents,” says Shaw. “Adult singletons will often say that they wish they’d had siblings simply because there was just too much attention directed at them.”
This phenomenon can occur in all one-child families anywhere in the world, but it’s most evident in China, where the government has been conducting a decades-long, population-wide, longitudinal study in only-child science. In 1979, China, facing a rapidly exploding population, implemented its notorious one-child policy—or, as the ruling Communist Party called it, its “policy of birth planning.” Parents were offered financial and employment incentives to stop having babies after producing just one—and threatened with penalties for failing to show such reproductive restraint.
Even in a country as regimented as China, such a sweeping socialengineering project was never going to be easy to police, and the one-child policy has indeed been inconsistently applied. Enforcement has been much stricter in cities than in rural areas, and some ethnic minorities, who make up a relatively small fraction of the population, have been exempted altogether. Parents have gamed the system on their own, sometimes in terrible ways. With the advent of in vitro screening methods such as ultrasound, for example, came the practice of selectively aborting girls and trying again to have a boy—a likelier route to family wealth and prestige. Families that do bring a daughter to term sometimes abandon her immediately after birth, a practice that fueled the overseas adoption boom as streams of baby girls left China for new families in the West.
Thirty years of such demographic manipulation have had a profound impact on China’s population. To date, an estimated 250 million Chinese babies who otherwise would have been born never were. Among those children who did make it into the world and remained in China, there is currently a badly lopsided gender balance, with 32 million more boys under twenty years old than girls. That disparity will be more acutely felt over the coming years as the boys reach marrying age and find that there are just too few girls to go around, leading either to a permanent sub-population of bachelors or an unplanned-for surge of emigration as millions of young men go overseas to find wives and raise families.
That’s for the future, though. For now, the lives of the Chinese singletons—particularly the boys—have more than enough challenges. The one-child policy has given rise to a generation of what are known in China as the xiao huangdi, or “little emperors,” children from preschool age to young adulthood who think the suns and stars of Chinese culture revolve around them—in part because they do. They attend the best colleges, snag the best jobs, and in a new and exuberantly capitalist culture, grow up to make the most money. A 2004 article in Fortune magazine that explored the xiao huangdi in depth quoted a consumertrends analyst from Ogilvy & Mather saying, “Get ready for the biggest me generation the world has ever seen.”
Chinese critics themselves take a similarly dim view of the little emperors. The same Fortune story cited the common complaint among adults that singletons never learn to “eat bitterness,” or overcome hardship and obstacles. Said one kindergarten director, who knows better than most how the xiao huangdi see their place in the world: “Kids these days are spoiled rotten. They have no social skills. They expect instant gratification. They’re attended to hand and foot by adults so protective that if the child as much as stumbles, the whole family will curse the ground.”
While that might seem like an enviable arrangement for the only children themselves, such a constant lavishing of attention does not come free. Children offered the opportunity to attend the best schools are also expected to do so—and to thrive there. The availability of the best jobs includes an assumption that the singletons will actually land them and get rich performing them. Billboards exhorting the only child to work hard dot the countryside, and teachers and bosses repeat the message over and over again. By some measures, the xiao huangdi may not be little emperors at all, but rather something more like little salarymen—China’s youthful version of Japan’s overworked, overpressured, badly stressed young executives of the 1980s.
“These children aren’t spoiled,” says Toni Falbo of the University of Texas, Austin, who traveled to China on a grant from the National Institutes of Health and studied 4,000 children in both the cities and the countryside. “They’re just pressured to achieve. They’re told to be obedient, to work hard, that the whole fate of the nation rests on them. That’s the normal discourse.”
The Chinese experience, of course, is entirely different from the American one—or, for that matter, from that of most other countries. But down at the level of the individual family, only children in any part of the world can surely sympathize with the sense of parental expectation and family responsibility experienced by singletons everywhere.
“Sometimes, I felt like I wasn’t just my parents’ only son, I was also their only sun,” is how Tom Everett, fifty-two, an investment banker living in Denver, has often put it. Everett is in the relatively uncommon position of not only having grown up as a singleton but being the father of one himself. “Only children become the focus of what’s going on in the family, good or bad. In my household I felt like if I was doing well, everybody would be doing better.”
But there’s a paradox at work, too. Such pressure-cooker living ought to be something that adult singletons recall with sadness and even resentment. On balance, however, Everett describes his solo upbringing as “more positive than negative”—and he’s by no means alone. The majority of only children report that while they’re quite aware of the fun they’d have had with a brother or sister—and quite candid that they would have liked that experience—they prefer the childhood they had. This is more than the simple human tendency to put the best possible gloss on something you can’t change anyway. People who grew up in a home with only one parent, after all, rarely say they wouldn’t have preferred two. Only children, by contrast, usually liked things just as they were.
You don’t have to be Hall or Brill to wonder how that can be. Finding the hidden benefits that make an only child’s upbringing such a positive and often fondly remembered thing has been a focus of much of the modern research. And it’s Falbo who has made some of the most important contributions to this growing body of work.
The biggest and most influential of her investigations took place in 1986, and most of the research published since has validated her bedrock findings. Falbo’s study was what’s known as a meta-analysis—not a separate body of work in which she recruited her own sample group and conducted her own surveys, but rather a round-up and recrunching of the data from multiple existing papers. In this case, there were 115 of those studies, all revolving around singletons. Falbo strip-mined the data from those papers and then reapplied it in a new way, evaluating singletons in six critical categories of her own devising: achievement, intelligence, adjustment (including self-esteem and behavioral issues), character (including leadership skills and maturity), and sociability (including extroversion and ease of affiliation with peers). She also looked at the quality of the children’s relationships with their parents.
No matter how Falbo analyzed her numbers, not only did she not see the terrible developmental deficits singletons are supposed to suffer, she actually found that they matched or exceeded the performance of children who grow up with brothers and sisters. In achievement and intelligence, singletons did better than most kids from families with three or more children, finishing behind only firstborns and children from two-child families—and then not terribly far behind. (The fact that firstborns and kids from two-child families have a slight edge probably comes from the opportunity the older child has to mentor the younger one, and the exclusive attention the younger one gets from the older.) Singletons surpassed all kids from multiple-sibling families in character and the quality of the parent-child relationship. In adjustment they finished slightly ahead of all kids with sibs, and in sociability they finished slightly behind, but in both cases the difference was so tiny that it was, for statistical purposes, a tie.
“Overall, only children were not different from the others,” Falbo says. “Even though the assumption is often that they will be introverted and loners, there just didn’t seem to be any association at all. In intelligence, sociability, and adjustment, they were pretty much like everyone else, and what little differences there were, actually were an advantage for only children.”
Some of the qualities Falbo sought to study are admittedly hard to measure. It’s not easy to find a precise metric to apply to qualities as vague as character and adjustment. But traits such as achievement and intelligence can be quantified down to the decimal points, thanks to IQ tests, SATs, grade point averages, and other academic yardsticks. And it’s easy to explain why singletons score so high. Not only do they get more educational opportunities, they also grow up in a home that is simply more intellectually stimulating than one in which parents are raising multiple kids.
A single child outnumbered by grown-ups tends to strive harder to understand adult vocabulary and interests—a very different situation from the one in the multiple-child home in which the kids tend to tug the grown-ups down toward their sophistication level. Everything from the music singletons hear to the DVDs they watch to the conversations that swirl around them over the dinner table is likely to skew older. When the choice is to adapt or be left out, the singleton does what’s necessary. A 1982 study that preceded Falbo’s meta-analysis confirmed this fact when scientists observed mealtimes in only-child homes and multiple-sibling homes and tallied up the discrete bits of information and back-and-forth conversation that took place—separating it out from periods of silence or utilitarian exchanges such as “Pass the peas.” Again and again they found that the conversations in the singleton households were more consistent and more data-rich than in multi-sib families, and it was the parents who set the tone and the topic. Everett became aware of this phenomenon early in his life—and today is happy for that experience.
“There wasn’t a built-in language and sensibility of children dominating my household,” he says. “As a result, I quickly got comfortable with how adults think and speak, and often did so a lot faster than my friends did. That included what we watched on TV. When I was growing up, most of my friends watched shows aimed at kids. In our house it was things like The Dick Van Dyke Show. It was a very sophisticated show—very subtle and smart. It taught me what was funny, and why things are funny. I watched a lot of politics, too, because my parents were watching things like that. What I didn’t see much of were cartoons. That’s the way things are in my house now, too. My son is only ten, but his favorite thing to watch on TV is reruns of Friends. He enjoys it—and he also understands it.”
The vaguer measures of singleton accomplishment, such as character and adjustment, are not quite as easy to explain as intelligence and achievement, but in some respects the very mechanisms thought to do only children harm may in fact be the ones that confer extra benefits. Parental attention, for example, can indeed sometimes become doting, which is not good for any child. However, when moms and dads are very attentive to a child’s needs, the child in turn learns that opening up in times of emotional distress—seeking and receiving help—is much preferable to covering up.
Similarly, the fact that singletons spend more time alone than other kids may make them not less socially successful but paradoxically more so. When you’re more familiar with being alone, you’re also more comfortable with it, which reduces the urgency and anxiety many kids feel in trying to find and join a social group. Singletons may make wiser choices in these situations, simply because they’re content to wait until the right group comes along.
Other variables, less within the control of singletons and their parents, can determine the developmental trajectory of the only child. Being lucky enough to have a large extended family is one of them—particularly if those family members live nearby and include a lot of cousins who are close in age.
In wealthy, highly industrialized countries like the United States, easy mobility and frequent job switching mean that extended families are rarer than they once were, but they remain more common than many people think. One analysis from the Pew Research Center shows that 37 percent of Americans live their entire lives in the community in which they were born. Many of those who do move away don’t go very far: As many as 80 percent of people born in New York State, for example, will never live outside of the state, a loyalty to place followed closely by natives of Louisiana, Pennsylvania, Michigan, and Ohio. The rest of the nation does not trail far behind. All that keeps extended family close at hand, and all that is a good thing for singletons, for whom cousins—and even young aunts and uncles—may become surrogate siblings. Indeed, in some ways having cousins may actually be better than having siblings, providing much of the same brother-and-sister companionship without any of the fighting, jealousy, and competition for Mom’s and Dad’s attention and the resources that go with it.
The near absence of such familial surrogates is one more reason China’s one-child policy has been such a demographic disaster. Many young parents were themselves products of one-child families, which means that huge swaths of the newest generation of families have been entirely stripped not only of multiple sibs but of uncles, aunts, and cousins as well. That has never gone down well in a country that has long celebrated the centrality of the family and the awareness of ancestral lines, never mind the fact that it also starves only children of bloodrelative playmates.
American singletons enjoy other advantages, particularly since the early 1970s, as more and more women joined the workforce and periodic recessions have increasingly made a one-income household impossible to maintain. With both parents punching a clock, day care and preschool have become not just luxuries but necessities. Big companies with generous benefit plans sometimes provide on-site day-care centers or help employees pay for outside care. Even when companies don’t chip in, parents themselves have made day care a family priority, placing it high on the list of mandatory household expenses such as groceries and electricity. Some have established parenting circles or community groups that provide a form of collective care, with moms and dads in multiple families taking turns volunteering their services.
In much the way the immune systems of kids in day care are thought to boot up earlier and more vigorously because they’re exposed to colds and other bugs more frequently than kids who stay at home, so, too, are the social skills of singletons brought online faster when they spend all day in the company of other kids. A similar pattern of formal socialization continues as singletons move out of day care and into grade school and beyond. Many child-care professionals rightly lament the mad overscheduling of after-school activities that increasingly begin for all contemporary kids even before they hit first grade—the nonstop dash from soccer to gymnastics to swim class to chess club. But all the frenetic scheduling does have a particular benefit for singletons, giving them more opportunities for connecting with other kids after the school bell rings than they would get if they were simply going home to a house in which the only other people are adults.
Certainly, none of this means that even the most sanguine psychologists or the most well-adjusted singletons would be likely to argue that growing up without siblings is, as a hard rule, preferable to growing up with them. The mere fact that so many only children find so many compensations for their lack of brothers and sisters doesn’t mean there wasn’t something missing that had to be to compensated for in the first place. And the absence of a sibling does leave a hole that the singleton must work to fill.
But in that very act of compensation there can also be a quiet reward. Of all of the traits parents and psychologists admire in only children, it’s the kids’ comfort inside their own skin that is the most striking—an autonomy and self-containment that allow them to amuse themselves, to find deep, even contemplative pleasure in reading or fantasy play or whatever else is absorbing them at any moment. There’s a texture and richness to that kind of total-immersion learning that might not be possible if the same kids had to cope with the distraction of a group of noisy sibs fighting or roughhousing or otherwise drawing their focus. It may be coincidence that history is full of great thinkers and artists who emerged from only-child homes—Da Vinci, FDR, Elvis, Cole Porter, Lillian Hellman, Frank Sinatra, Cary Grant—or it may be that the time and attention they were able to devote to developing their innate talents helped push them across that elusive line that separates simply being good at something from being truly extraordinary at it. The freedom to breathe and think and focus on one thing at a time is something that most people experience too rarely. For singletons, it can be a simple part of life.
“I watch my son and am always impressed by how comfortable he is with alone time,” says Everett. “He may be reading, playing with Lego, practicing guitar, but whatever he’s doing, he becomes completely involved with it. I’m happy he has that ability to entertain himself and deal with some of his own needs. Would that have been the case if he’d had a brother or sister? Maybe—but I don’t think so.”
My sister, Allison, wore a lavender jacket the night she went out to throw eggs at cars on Park Avenue. It was a new jacket, down-filled, and would have to last her the entire fall and winter season—which, on Halloween night, had barely begun. For that reason, her mother had told her to take especially good care of it. She had no idea Allison would be wearing it tonight when she went out for what was supposed to be an evening of innocent trick-or-treating with her twin brother, Adam, but was actually an evening of misdemeanor mischief with him and a group of his male friends.
It was 1997, and Allison was thirteen and not usually the type to make misdemeanor mischief, but this evening she made an exception, partly because she liked being accepted as a member of Adam’s little wolf pack of friends, and partly because Adam himself would be there. As a general rule, any place on the planet one of them went was the place the other would want to be, too. So they went out egging together on Halloween night, and were neither hurt nor arrested in the process—though the lavender jacket got fairly splattered—and slipped back inside without incident.
The next morning, Adam and Allison would return to very different—and very familiar—roles. Allison would wake up for school first and go into Adam’s room to make sure he was awake. She’d return to her room to get dressed, checking the clock periodically to keep them from running late. When they sat down to breakfast she’d watch him to see that he ate and would ask him if he’d done all his homework for the day. She thought of herself as a little mama and, though she never said it out loud, Adam seemed to see things that way, too. My brother and sister may have been playmates, confidants, co-equals, and best friends, but when it came to the routine business of daily living, she was the one who kept their trains running on time. That was simply the way things had always been—and it was completely typical of the complicated world of twins.
If singletons are the free radicals of the sibling world—the unpaired electrons that must bounce around in search of a bonding site and a stable state—twins may be the steadiest and most grounded of elements. Conceived in tandem, bonded in the womb, they share the world before they’re even fully part of it. Fraternal twins, from the geneticist’s perspective, are nothing terribly special, a random mix of their parents’ genes, who may share anywhere from 10 percent to 90 percent of their own genomes, but who most of the time will shake out at about 50 percent—which makes them not a whit different from any other full siblings. Of course, other siblings don’t seem to be able to read each other’s minds and finish each other’s thoughts and have no idea how they would proceed in a life in which their twin wasn’t at their side—which is how fraternal twins themselves often experience things.
Identical twins are something even the geneticists can’t wave off. They’re as close as an arbitrary thing like nature can come to qualitycontrolled mass production—two humans stamped out from identical templates, with identical strengths and identical weaknesses, all run by an identical genetic operating system. Identical twins start life as a single cell before dividing into a pair of independent embryos, which means that not only are they similar entities, for a brief time they were the same entity. Growing up in a world with a photocopied self always at hand is something only the copies themselves can fully fathom—an experience that is at turns warm, fierce, rich, complex, and surreal.
Being a twin is by no means an unalloyed good, and both identical and fraternal pairs can start life with a lot of disadvantages. Childbirth alone can be more fraught when twins are being delivered, with a greater chance of complications and even maternal or infant death, particularly in the developing world, where labor and delivery are less likely to take place in a hospital. But even in the most high-tech setting, there can be problems. For starters, twins have a higher risk of being undersized at birth and are also likelier to be born prematurely. About 60 percent of twin pairs are premature, according to the March of Dimes, and more than half are low-birth-weight babies—five and a half pounds or less. The prematurity figure for triplets is 90 percent and close to 100 percent for all larger broods. Premature and undersized newborns are likelier to suffer from a host of problems such as respiratory disorders, heart disorders, intestinal problems, and abnormal retinal development. They are also often found to have lower IQs—though that can change over time.
This is generally so whether a mother of twins is carrying a pair of boys, a pair of girls, or a boy and a girl, but in cases of mixed-gender twins, there can be other developmental wrinkles. Premature twin boys have a 60 percent greater likelihood of developing respiratory disorders than premature twin girls do. The reasons are not entirely clear, but they are likely part of the overall edge in hardiness female humans enjoy over males throughout life—an edge that contributes to their lower incidence of disease and generally longer life spans. In terms of postpartum respiratory disorder, however, things change when a boy and girl share the womb. In those cases, the girl loses her edge, facing the same increased odds her twin brother does. This shift in risk has long been reported anecdotally, but a 2008 study from Tel Aviv University documented it, examining records from 8,858 births of very low-birth-weight infants (one to three pounds) from 1995 to 2003 and finding the mixed-twin respiratory phenomenon again and again.
The explanation for the problem may lie in hormones. Fraternal twins develop in separate amniotic sacs and have separate placentas. Identical twins may or may not have separate placentas, depending on when the two embryos divide; they will only very rarely share the same sac—from 1 in 35,000 to 1 in 60,000 pregnancies. Nonetheless, during gestation all twins do share the same womb environment, and the crossmixing of chemistry that inevitably takes place can have an effect on development. A growing body of work is showing that this can be particularly so in terms of gender, with girls exhibiting a subtle masculinization when their twin is a boy. Behavioral studies of boy-girl twin pairs often find that the sisters tend to take more risks, exhibit more outgoing behavior, and generally behave in more dominant ways than other girls. Like my sister, they also tend to assume a parental role relative to their brothers.
Risk taking, of course, could simply be learned—a result of growing up side by side with a boy. And looking after a brother may just be caretaking and early mothering behavior. But Nancy Segal, a psychologist at California State University at Fullerton and author of two books about twins—Entwined Lives and Indivisible by Two—does not think so. She is especially struck by studies in which boy-girl twins raised apart are compared to boy-girl non-twin siblings who were raised together in a way that made them what she calls “virtual twins,” adopted into the same family at the same age and same time, for example. In general, the girls in the biological boy-girl pairs showed more dominant and assertive personalities—even growing up without their brothers—than the girls who technically had no twin sib but grew up as if they did.
What’s more, Segal says, otoacoustic emissions—the sound waves given off in sex-specific frequencies by the inner ear structures of all people—are male-shifted to a deeper frequency in girls who have a male twin. That’s similar to the otoacoustic shift that has been found in some studies of lesbian physiology, which may suggest a similar hormonal influence in determining sexual orientation—though in cases of single births the reason for that change in chemistry is not clear.
“The subtle masculinization of a female twin has been shown in cattle, too,” Segal says, “though they have a different placental arrangement, which means that it’s not a perfect analogy. Still, in humans, there can be some blood sharing, and that’s probably where things begin.” A similar body of work has not yet been done on whether there is a corresponding feminization of boy twins in the boy-girl pair, though there’s little reason to believe that the phenomenon should run only one way.
The blending of twins’ body chemistry is nothing compared to the sometimes eerie blending of their minds. Anecdotes of a sort of twin telepathy are everywhere among families raising both fraternal and identical pairs—and that includes my own. One afternoon after my sister had grown up and gotten married, she was out driving with her husband while Adam was away visiting California. She suddenly found herself overcome by a powerful unease, one she could neither account for nor control. She mentioned it to her husband, who suggested that perhaps she should call Adam when they got home to see if he was all right. She did—and he wasn’t. He had broken his ankle riding an all-terrain vehicle over sand dunes with his friends, and had done so at more or less the very moment she was feeling so jumpy—nearly 3,000 miles away.
Mothers whose sons are off at war have long told similar tales of knowing when a child has been wounded or killed, and the natural impulse in both these situations is to credit moms and twins with a sort of supersensory ability, a paranormal connection to the people who mean the most to them and an innate awareness of when something has gone wrong with them. Maybe. Or maybe something less wondrous is happening. Human beings are notoriously selective observers, living in a world in which cause and effect can be hard things to measure. You set your alarm clock for 6:00 a.m. every day and not long after it sounds, the sun rises. The unmistakable implication: If you forgot to set the clock, the sun would not come up. When free-floating anxiety precedes a terrible event, the causation feels obvious and the experience becomes filled with meaning. When free-floating anxiety precedes nothing in particular, it may dissipate as inexplicably as it appeared and soon be forgotten altogether.
But even if the feeling of mother and twin intuition can’t be explained magically, it can still be explained meaningfully. For many twins, the partner with whom they entered the world will always remain at its emotional center. In the best cases—most cases, actually—that does not crowd out the love they later feel for spouses and children, nor prevent them from building nuclear families of which the twin is not the central part. But nor do those later relationships ever diminish the one with their birth mate. “Allison has always been and will always be my very best friend and soul mate,” is how my brother Adam—not usually given to hyperbole—puts it. “I have other best friends and soul mates, especially my wife. But there is only one Allison. I am who I am because of her.” Unease when that soul mate is away or out of touch is to be expected, and the anxiety that precedes cases of seeming intuition is more likely to occur in those on-your-own periods.
Powerful as the emotional bond is between fraternal twins, it is usually even more so between identicals. Indeed, for these pairs, the closeness of the twinship does sometimes surpass all other relationships either twin will ever form. “When they’re asked, more than 99 percent of identical twins will endorse the idea that ‘My twin is my best friend,’” says research psychologist Tony Vernon of the University of Western Ontario. “Even if they haven’t seen the twin in a while, they’ll admit to being closer to that brother or sister than they are to their spouse or their children. And when a twin dies, the bereavement the survivor feels can be worse than for all other family members, too.”
That grief typically comes late in life, because identical twins also tend to enjoy an edge in longevity over other people, with an average life span of 82, compared to 80.5 for fraternal twins, and slightly under 80 for Americans as a whole. The reason twins get the edge: They tend to stay in closer contact throughout their lives, even if they live in different cities. Remaining socially connected to other people is one of the greatest predictors of longevity among older people, while isolation is similarly predictive of mortality. Twins also have a substantially lower rate of suicide than the general population, according to a 2003 Danish study that tracked a whopping 21,653 pairs of same-sex twins for an equally impressive fifty-one years. That happy stat was also attributed to stronger family ties.
The fact that twin communication can be a special thing is no surprise to parents raising both identical and fraternal pairs, in part because twins often seem to have a language of their own—literally. Lisa Dreyer, mother of eight-year-old fraternal twins Sofia and Alejandra, noticed just such a thing before her daughters were even fully verbal.
“When the girls were just learning to speak, they had basic, oneword commands for my husband and me, and those were pretty clear,” she says. “But I also noticed a specific pattern and inflection in their speech when they spoke with each other. They didn’t do this in public or around adults, but mostly when they were in their cribs, which were side by side in their room. One of them would babble, which would make the other one laugh or react with similar babble. My husband and I would stand outside their room listening to this, absolutely stunned because it was clear they were having what sounded like a conversation. This lasted until they were almost three years old and it ended when they got to school. When I ask them about it today, they say they don’t recall it.”
Tempting as it is to think the girls actually were communicating in a whole new language, there’s probably something subtler and, alas, less remarkable going on. “Twin language always fascinates parents,” says Lisabeth DiLalla, developmental psychologist at Southern Illinois University School of Medicine. “Most twins don’t exhibit this, but many do. What sounds like some magical language, however, really isn’t. It’s English but in a kind of shorthand that’s so familiar to the twins they need no translation. This happens mostly in preschool or the early school years, before they start communicating more with teachers and other children.”
Twins collaborate behaviorally in other ways. Early on, Dreyer and her husband noticed that, once their girls developed their full verbal skills, they were equally talkative—but only when they were playing together or communicating with family members. Out in the world, Sofia usually spoke for both of them. Of the two, she was inherently the one more socially at ease and simply assumed the responsibility of serving as their spokesgirl. Alejandra was perfectly happy with such an arrangement and permitted it to take place. By the time the sisters got to grade school, however, the roles changed. Both of them had learned to speak for themselves, but now it was Alejandra who was more gregarious and Sofia who was more reticent.
Here, too, the girls are not uncommon. Twins often follow a shared but staggered maturation arc, with one sib developing a particular skill while the other lags. The sib who has fallen behind then catches up. Eventually, they accumulate all of the abilities they need, but for a while it’s as if they’re collaborating on just one personality, dividing the labor in the service of a single whole. “You see an interesting kind of turn taking,” says DiLalla. “I’ve had moms come in and point to one twin and say ‘This year she’s the outgoing one, but last year she was the introvert.’ It’s not that their personalities aren’t developing. It’s that they have each other, so things develop differently.”
All of these things are true of both fraternal and identical twins, but identicals do share a greater degree of intimacy and overlap than even the closest fraternals ever could. This is largely attributable to their matching genes. It’s here that their connection can often seem truly otherworldly. The Minnesota Twin Family Study (MTFS) is an ongoing research project sponsored by the University of Minnesota to investigate how twins differ; how they’re similar; and in what ways genetics, environment, or both are at play. The MTFS has been under way since 1983, amassing a large registry of twin volunteers and a vast and growing library of data. Some of the most compelling results they’ve produced concern identical twins who were separated at birth and raised apart—perfect lab specimens for the dual influences of environment and heredity, since they share all of their genes but virtually none of their experiences. The power of those genes has proven to be extraordinary.
Among the cases MTFS researchers most like to cite is that of the Jim twins—identical brothers who never knew each other and were raised by separate parents. It is surely just coincidence that both sets of parents chose to name their babies Jim, but the parallels never seemed to stop after that: The Jims grew up to smoke the same brand of cigarettes, drink the same beer, drive the same car, and have the same opinion about baseball (they didn’t like it). They married women who also had the same names, divorced them, and married other women—with matching names again. They went on vacation to the same resort at the same time, though they did not bump into each other there—and indeed never met at all until they were united by the study.
Selective observation and randomness may again be at work here; the identical names of the Jims’ wives were surely no less happenstance than their own matching names. But there are other twin pairs who offer examples of similarly strange convergence. There are the identical girls separated at birth who both grew up to enjoy writing in journals—and both, when the journals were later compared, had chosen the same days to write and the same days not to write. There were the twin boys born in prewar Germany to a Jewish father and a non-Jewish mother. One left Germany, one remained, both survived—and both grew up to enjoy making funny noises in elevators. There were the two male twins who both grew up to be firemen, the two who developed the odd quirk of flushing a toilet both before and after using it.
Every bit of this may be mere chance, but at least some of it may not be. If it isn’t, the explanation for what’s going on does not have to lie in anything supernatural, but rather in the software that is the human brain. “Identical twins have similar—indeed identical—brain wiring,” says Vernon. “They’ll have matching electroencephalograms, and their brains typically operate in matching ways.” That means their temperaments are likely to be similar as well, and that in turn will drive them to make similar choices.
Twins who smoke the same brand of cigarettes may do so strictly by accident, or both may share brain wiring that makes them innately outgoing and rebellious. That could push them to choose uncommon brands other people don’t, smoking Dakota cigarettes, say, and drinking Shiner Bock beer. Twins who are both innately quiet and conformist may both go for Marlboro and Budweiser. The same kind of temperamental tendencies could also drive geographically separate twins to develop similar views on baseball or politics and to choose either a conservative sedan or a zippy roadster as the family car. Twins who need constant emotional stimulation and activity may both like the buzz that comes from living in cities, and thus find themselves in a lot of elevators; if they’re also mischievous by nature, they may decide it’s fun to make noises there, too. Twins who are prewired to be thoughtful and reflective may be identically drawn to journal writing, and the parallel hormonal and metabolic cycles that carry them through the month may prod them to write on the same days.
Matching brain wiring presents twins with matching challenges, too. Vernon’s studies have found that identical twins, whether raised apart or together, correlate more than any other sibs for a behavioral trait known as negative affect—or the simple tendency to complain, overreact, and exhibit bad moods that often cloud the good ones of the people around them. Identical twins also have similar scores on a test known as the Dimensional Assessment of Personality Pathology, which measures what psychologists call “the dark triad” of behavioral traits—Machiavellianism (or deceit and manipulativeness), narcissism (which includes not just self-absorption but a sort of exploitative seductiveness), and simple psychopathy. Fraternal twins may correlate on all of these traits, too, but identicals do so at about two and a half times the rate. That means that “to the extent that identical twins do correlate, those correlations are often linked to genetics, not environment,” Vernon says.
Most parents of twins do not have to reckon with such pathologies, since even among the twin population, the conditions remain comparatively uncommon. For them, the routine challenges of raising twins—fights, rivalries, learning to share, going to school—are more than enough. It’s almost never easier raising two at once than one at a time, particularly in babyhood, when the work includes diaper changes and round-the-clock feedings. Just how big the workload remains as the twins get older often depends, again, on whether they are identical or fraternal. Identicals, as a very general rule, will be more cooperative and collaborative; fraternals will be less so—and that means that fraternals will fight more, too.
Nancy Segal cites a German study in which pairs of twins were given tasks to perform, such as completing an art project or solving math problems. Each twin worked independently of the other on a separate sheet at a separate table. When identical twins were being studied, they tended to coordinate their work without even seeming to plan it—moving at about the same pace and finishing at about the same time. When fraternals were involved, things became more of a race to see who would finish first and who would perform better. If the skill being tested happened to be one at which only one of the fraternals excelled—drawing a picture, say—the one who didn’t have the same level of ability would sometimes not even try. For Segal’s own doctoral dissertation, she ran a similar study, but this time she had the twins work together, at the same table, on a single jigsaw puzzle. The differences could not have been more stark.
“The identicals were well coordinated,” Segal says. “They were happy and it was almost like they were dancing. The fraternals were more competitive and argumentative and not well matched. They were a mess.” Segal has interviewed identical twins who were both artists and worked together on projects, and has seen a similar collaborative talent at play there, too. By the time the pairs were done working, they sometimes couldn’t even say which twin had contributed what to the work.
(Such collaborative intimacy is more common among identical twins than among fraternals or non-twin sibling pairs, but it’s not exclusive to them. Joel and Ethan Coen—two years apart and creators of such films as Fargo, Raising Arizona, and the 2007 Oscar winner for best picture, No Country for Old Men—are very clear in their screen credits about who does what job, with Joel listed as director and Ethan as producer. But the brothers actually collaborate much more than their screen credits let on, often sharing directing and producing chores. They even co-edit their films, though under the pseudonym Roderick Jaynes. How well is that collaborative editing working out? Consider this: “Jaynes” has twice been nominated for an Academy Award—once for Fargo and once for No Country for Old Men. If he ever wins, Oscar officials plan to accept the award on behalf of the Academy.)
With larger broods of multiple siblings—triplets, quadruplets, and beyond—things are, no surprise, exponentially more complicated than they are with twins. For one thing, not all sibs in a multiple birth of three or more will be fraternals. Sometimes there will be an identical pair thrown in. That’s not quite so bad if there are at least two fraternals to go along with them. But when the brood is triplets and the breakdown is two identicals and one fraternal, that odd child may always feel a bit left out.
“When you have this arrangement, the identicals will usually be closer than the fraternal,” says Segal. But, she stresses, that’s not always the case. “I talked to a woman who has boy triplets with an identical pair and one fraternal, and the identicals didn’t get along. Instead, they both pal around with the fraternal.”
Triplets as well as larger groups may also practice the tactic of triangulation—as when two sibs form an alliance that excludes, or sometimes even punishes, the third. Triangulation can occur among all members of a family, and is especially common when marriages are in trouble and children strategically align themselves with Mom or Dad, using their loyalty as a lever to get what they want from the parent they’ve selected. Among triplets and other large sibling groups, these allegiances can shift with the circumstances, so that while all of the kids will get a chance to be part of the bonded group at some point, they all will also be excluded at others.
The precise dynamics of triplets and other larger sibships is, for now, only poorly understood, mostly because such extreme multiples are so rare. About 1 out of every 32 births produces twins, compared to 1 out of every 535 for triplets and above. In vitro fertilization techniques have caused this number to jump in recent years, but the boom in multiples has eased some as doctors improve their techniques and are better able to ensure that parents who want only one or two children get them.
No matter the actual head count in a multiple-birth brood, the bonds among all the kids will typically follow the pattern with twins, which means that they will all grow up closer than even the most well-matched single-birth sibs. This closeness—which is usually a very good thing—can present other challenges that parents must learn to manage. DiLalla cites studies showing that two- and three-year-old identical twins tend to be shyer than other kids; she conducted follow-up research of her own in which she recruited 100 pairs of non-twin sibs and 80 pairs of twins and evaluated their temperaments and prosocial behaviors. She found that preschool twins indeed tend to be less social, and when they move toward adolescence, they are more prone to be aggressive as well.
Much of this is due to the mere fact that twins are less motivated than other kids to seek out friends outside the home, since their best friend already lives under the same roof. When they finally do begin forming relationships with other peers, they are less skilled at it. “It sort of all fits together that there may be something going on in which twins are being less socialized rather than more,” Segal says of findings like DiLalla’s.
One solution, of course, is to nudge the twins apart. Parents often tie themselves into knots worrying about how similar they should allow—or force—their twins to be and how much they should try to help them establish separate identities. It’s not just dressing them alike, it’s taking them to the same after-school groups, providing them with the same toys or books, and introducing them into the same circles of playmates. It can even include whether or not to give them similar names—the Jane and June, Ed and Fred, Andy and Mandy phenomenon.
No matter how much or how little parents allow twins to have in common, the world outside the home will insist on seeing them as two of a kind. “Regardless of whether twins are identical or fraternal,” Kramer says, “people look at that dyad a different way. There’s a belief that they’re more connected to one another and that they understand one another.” That creates a certain pressure on the kids to live up to that stereotype.
Dreyer noticed just that public expectation early in her twins’ lives and came up with a few simple countermeasures. Even in the home, she and her husband never referred to their children as “the twins,” but rather as “the girls.” That’s something the girls themselves seemed to internalize. “If somebody asks them now if they’re twins, they’ll answer yes,” says Dreyer. “If someone asks them if they’re sisters they’ll say yes to that, too, but they won’t clarify further.” She and her husband also never dressed the girls alike and did try to help them develop different interests. In addition, they requested that they be placed in different classes at school, mostly to encourage the quieter twin to stop relying on the more gregarious one to speak for them both—a strategy that worked.
Opinions on whether twin sibs should be in the same classroom tend to differ from family to family and school district to school district. Is separating them the only way to give them enough breathing room to develop individual identities? Does keeping them together help them adjust better, at least when they’re very young? As a rule, there are no rules.
“Until recently, schools always made the decision,” DiLalla says. “But lately parents have been deciding and more schools are deferring to them. That doesn’t always mean the parents are right. Ultimately, it often comes down to the simple matter of whether the kids are well behaved or not. Twins who come into school showing behavior problems tend to do better when they’re separated. Those who don’t have these behavior problems may do better when they’re kept together.”
Such squishiness—maybe this, maybe that, maybe so, maybe not— does not do much to help parents who are looking for firm guidelines, and nor does the similar absence of fixed rules about dressing twins alike or buying them different toys or giving them separate rooms. The upside of this is that it simply may not matter. Over the course of a lifetime—a long one, given the extra years most twins get—they will make their own choices and find their own level of closeness. They will de-identify and reidentify, drift apart and drift together. The parents’ role in all of this will be necessarily limited, to act as what DiLalla calls “a scaffold.” What the twins build on that emotional framework will be entirely their decision. Much more often than not, they will build something lasting.