Accidental Bond: How Sibling Connections Influence Adult Relationships

"A fascinating and informative read."

*The Boston Globe



"A RICH SOURCE OF FASCINATING MATERIAL about the complex realities of siblinghood and a valuable commentary on the impact that these little-studied relationships have upon our lives."

*The New Republic



"Many books have attempted to tackle the complex theme of sibling connection. But rather than look at the minutae of these relationships, journalist Susan Scarf Merrell examines the big issues that all siblings wrestle with in their own unique ways *in particular the Three Cs: Competition, Cooperation, and Comparison. What she discovered was that no matter what kind of relationship we now have with our siblings *close or distant, loving or hostile *our histories with them exert a profound effect on our current relationship with lovers, friends, coworkers, and our own children. Drawing on the most current research; the work of psychologists, psychiatrists, and family experts; and stories from brothers and sisters themselves, Merrell illustrates that through siblings, we come to know both the worst and the very best that lurks within each of us.



"Susan Merrell brilliantly illuminates how the peculiar mix of biology, history, and intimacy makes our attachments to siblings so essential to knowing ourselves."

*Mary Kay Blakely

Author of American Mom

CHAPTER ONE
 
 
 
The Accidental Bond
 
 
 
We do not select our beginnings. We are cast from Eden when one of a million sperm connects, in a random instant, with an egg; our creation occurs because two previously unacquainted genomes—without benefit of clergy or even a moment for mutual assessment—select one another and marry for life. Such a wonderful intricacy of circumstance joins gene to gene, supplies the nascent human with the parameters of its adult personality and physical form. At that moment of primary connection, the person-to-be is endowed with propensities toward engineering or music, toward conversation or silence, toward athletic prowess or a fondness for animals or alcohol.
 
No one receives a gene to be a social worker or a murderer in the lottery of genetic chance; one’s endowment is a tendency toward a range of outcomes, not a blueprint for a single way of being. Such predispositions are further molded by life’s early lessons. At birth, a child’s world is given to him; the lessons of acting, reacting, and interacting will be learned with a certain set of parents, siblings, and others. The influence is mutual, for these others—each as inadvertently a particular self as any of the rest—react and change in response to the newcomer as well. And as each person evolves and grows, her relationships will influence the development of myriad aspects of her personality, from sense of self to ambition, talent, and energy. The basic self is a genetic inheritance, an accident of birth. In relation to others, then, each person becomes a more specific, durable individual.
 
A young mother gazes affectionately at her sleeping infant, and says, “She’s so peaceful; her brother was wild, he never slept.” The actual hours each child slept at six weeks of age may not be all that different, but the perception that the little girl is quieter than her brother—the family’s need to differentiate them in this particular way—will be one tiny factor that affects what sorts of people both children will eventually become. Nature’s bequest and nurturing’s behest work in concert: Our roots are immutable, but each tree grows in a unique way, depending on its response to the light, the care, and the room it receives.
 
That peaceful little girl, only a few weeks old, is already being affected and having her own effect on the world around her. Up until his sister’s birth, her two-year-old brother’s nickname, “Wild Man,” had always seemed a term of affection. At this moment, the accident of her birth has combined with his parents’ perceptions of critical characteristics to remake the world. Wild and peaceful are traits this family recognizes, while another family might focus on other descriptive terms—alert, curious, accepting, passive—that subtly alter the child’s sense of what is important. That big brother will never again know a universe in which aspects of his self and others will not be measured, at least in part, in relation to who his sister is or is not.
 
Shared and Unshared Environment
 
The urge to measure one’s accomplishments against those of a sibling is an ongoing feature of life, natural and normative. Even in adulthood, and despite the fact that so many of us no longer have a day-to-day intimacy with our siblings, we continue to regard them as yardsticks against whom our own achievements can be estimated. (Oddly enough, those “yardsticks” often fail to reflect who our siblings have actually become during their lives; rather, we tend to view them as grown-up versions of their childhood family labels.) Nevertheless, brothers and sisters tend to be so completely different from each other that comparing oneself to a sibling is a little like Albert Einstein assessing his accomplishments in terms of Florence Nightingale’s. Of course, one can draw such a comparison, but what purpose does it serve?
 
How can a set of siblings be so different from one another, since they all come from the same family? In order to understand our differences, we need first to look in the other direction, and examine to what extent children in the same family actually are similar. Conception, that first random bonding of sperm to egg, results in the creation of twenty-three pairs of chromosomes: One of each duo of chromosomes comes from the mother and one from the father. On each chromosome are thousands of different genetic components that determine different physical and psychological traits. For each minuscule genetic component, two siblings have, on average, a fifty-fifty chance of inheriting the same propensity. The range, researchers believe, is between 35 percent and 65 percent; thus, some sets of siblings are much more alike than others. (Note: Interestingly enough, siblings who are more alike genetically can actually tell that this is so at a glance; physical resemblance is a marker of genetic resemblance. And somehow those who have more in common know it: In one study, sets of twins were asked if they were fraternal or identical. Those fraternal twins whose blood analysis showed that they actually were more similar genetically than other fraternals were the ones who believed, albeit incorrectly, that they were identical.)
 
If siblings are 50 percent alike genetically, they are also 50 percent different. And yet, in fact, on most measures of personality, siblings are more dissimilar than that; in study after study, they have been shown to be far more unalike than alike. For more than a century, a series of devoted researchers has compared siblings on a huge variety of traits and characteristics. Since Sir Francis Galton’s first comparison of brothers and their relative heights in the 1880s, scientists have studied everything from height and weight to the incidence of cancer, from mental illness and alcoholism to personality characteristics such as liveliness, sociability, and moodiness. What they continually find is that siblings only rarely share more of a particular propensity or trait than random members of the population. For example, about 80 percent of brothers and sisters have different eye colors; hair color, hair curliness, and skin complexion are visibly different for a full 90 percent of siblings. One brother’s asthma, ulcer, or colon cancer has little bearing on whether his sibling will be vulnerable to the same illnesses. The story is the same for intelligence and reasoning abilities, although school success is also related to environmental factors, which tend to place siblings on a more even footing scholastically. Perhaps the sole measure upon which siblings have actually been found to be more alike than different is the question of whether or not they believe in the existence of God.
 
By looking more closely at a particular example, we can better understand the nature of the dissimilarities among blood-related siblings. Studies of schizophrenics, for example, have shown that the likelihood of a sibling also having the illness is about 10 percent. In the general population, the risk of schizophrenia is only 1 percent, so the risk is obviously higher for a sibling. But at the same time the most important thing to note is that 90 percent of siblings of schizophrenics do not themselves become mentally ill. That 90 percent figure holds true also for a range of illnesses, from breast cancer to Alzheimer’s disease to diabetes. Alcoholism, a tendency thought to be highly influenced by genetics, has a slightly higher rate; if one sibling is alcoholic, it appears that another will share the trait approximately 20 percent of the time.
 
One of the world’s leaders in sibling research, behavioral geneticist Robert Plomin, of the Institute of Psychiatry at the University of London, was among the first to grasp that siblings’ similarities are best explained by the genes they have inherited in common, while their differences are equally a matter of genetics and the environment in which they grow up. Thus, on average, 50 percent of the differences between any two siblings’ personalities is genetic in origin. The other 50 percent is a result of the environment in which the siblings are raised. As Plomin argues, two siblings only seem to have the exact same environment. Even if their worlds were identical—an unlikely event—each child would experience the world in an extremely individual manner. Furthermore, parents actually do treat each child differently, because they perceive each child to have different advantages and needs. And siblings, friends, and outside social and academic experiences continue to contribute to what is called “unshared environment,” that factor that makes each sibling develop so uniquely.
 
In this past century, during which geneticists have evaluated a great deal of evidence and become convinced of the vast differences among any set of siblings, much of psychological theory has tended to lump children into one rearing environment. Conventional thinking has always been that a mother has a single rearing style and treats each of her children in a similar manner; the father is assumed to be consistent as well. But parents act differently toward each child, a truth of which children are well aware. Consider that familiar battle cry: “It’s not fair!” Every child experiences a different set of parents, unique relationships with one another and with caretakers, teachers, and friends. Each child grows up in a world that only he or she perceives.
 
Even identical twins—who have precisely the same genes and enter the family at almost exactly the same moment in time—end up becoming unique, separate people with at least some different ideas about themselves and the world. Identical twins who select identical careers and marry identical twins will nevertheless have diverging self-definitions: One will be the “creative one,” one the “scientific”; one will be the cook, the other the seamstress.
 
In an often-quoted passage, psychologist and sibling expert Sandra Scarr of the University of Virginia makes this point:
 
Lest the reader slip over these results, let us make clear the implication of these findings: Upper-middle-class brothers who attend the same school and whose parents take them to the same plays, sporting events, music lessons and therapists, and use the same child-rearing practices on them, are little more similar in personality measures than they are to working class or farm boys, whose lives are totally different.
 
Siblings, to put it bluntly, are not at all alike.