Why we can never escape our siblings

New science sheds light on how birth order and brother-sister relationships shape our lives. An expert explains

Published September 10, 2011 10:01PM (EDT)

Sometimes a family tragedy can expose bonds you didn't know existed. That's what happened with my younger sister and me. Although just 11 months apart, we could not have been more different: I rebelled as hard as she conformed, and if you met us at a party ... well, that would never have happened, because we never went to the same parties. If we hadn't been forced to spend summers together with our dad after our parents' divorce, my sister and I would have spent scarcely any time together at all. Then my mom was diagnosed with Stage IV lung cancer and given less than a year to live. Suddenly, for the first time in our lives, my sister and I were not only inseparable but totally in sync.

Some patterns came naturally, since they were holdovers from when we were kids. Negotiating household chores was a breeze. I agreed to wash the dishes if she would dry and put them away. The next night, we swapped duties. Other moments of synchronicity caught us by surprise, like realizing we both avoid dealing with our emotions by taking on more responsibility. During the nine months my mother fought a losing battle for her life, she found joy in watching her daughters put aside their childhood differences and learn to appreciate each other as adults.

In "The Sibling Effect," science writer Jeffrey Kluger argues that the relationships we have with our siblings are the most important ones of our lives. From the time we gain a brother or sister, they can be both our fiercest competitors and closest confidantes. They teach us the social skills we carry for life and stand by us during our best and worst experiences -- divorce, the birth of children and our parents' deaths. In his book, Kluger uses the latest scientific findings to explain the meaning of everything from birth order to the stigma of the only child.

Salon spoke to Kluger about the enduring loyalty of siblings, why treating children the same is a bad idea, and the problem with being the middle child.

When you were researching the book, were you surprised by how intense the sibling relationship is?

The relationships I have with my siblings have always been very important in my life, but it wasn’t until 2005 that I began reading a lot of papers on the topic. The value and centrality of sibling relationships across the board was surprising to me, particularly because a lot of these dynamics are very deeply encoded. So many of the sibling dynamics we find in the home are replicated in the natural, non-human world, and so much of what I found is universal across several hundreds of species. When you get up to humans, we’ve embroidered and built on these dynamics in all kinds of elaborate ways, but human sibling relationships are deeply rooted into the evolutionary chain.

Is this why you make a strong case for people staying close to their siblings?

One of the reasons I made that case is that there is a real uniqueness to sibling relationships that people never fully appreciated before. Siblings are the only relatives, and perhaps the only people you’ll ever know, who are with you through the entire arc of your life. Your parents leave you too soon and your kids and spouse come along late, but your siblings know you when you are in your most inchoate form. Assuming you all reach a ripe old age, they’ll be with you until the very end, and for that reason, there is an intimacy and a familiarity that can’t possibly be available to you in any other relationship throughout your life. Certainly, people can get along without siblings. Single children do, and there are people who have irreparably estranged relationships with their siblings who live full and satisfying lives, but to have siblings and not make the most of that resource is squandering one of the greatest interpersonal resources you’ll ever have.

So what do we learn from our siblings?

You can think of what goes on in the playroom as a long-term, total-immersion dress rehearsal for life. There is a lot of real-time nimble improvisation that goes on when we’re learning how to deal with different relationships and conflicts as they come up, as well as how to embrace and settle into happy moments. When you learn conflict-resolution skills in the playroom, you then practice them on the playground, and that in turn stays with you. If you have a combative sibling or a physically intimidating, older sibling, you learn a lot about how to deal with situations like that later in life. If you’re an older sibling and you have a younger sibling who needs mentoring or is afraid of the dark, you develop nurturing and empathic skills that you wouldn’t otherwise have. This comes down to our basic interpersonal software, and our siblings help lay it in.

Does the sex of our siblings, whether we have brothers or sisters, make a difference?

The sex of siblings matters a lot. There is a lot of empirical truth to the popular wisdom that you can tell a boy who grew up with sisters and a girl who grew up with brothers. There is ruggedness, a winking lack of complete seriousness or grimness, to a girl who grew up with brothers. There’s a greater degree of sensitivity and listening skills in boys who grew up with sisters. Studies show that when you pair people up in 5- to 15-minute conversations, as if it were a speed date, the males who grew up with sisters tend to do better than the ones who grew up with brothers or as only children. Similarly, the females with brothers tend to do better with boys. This is because you learn a little bit about how to turn the tumblers of the opposite sex. Your relationship with your sibling is obviously very different than your relationship with a potential romantic partner, but you still learn how the mind of an opposite-sex peer works, and those skills are relatable to the outside world.

Why are we so interested in what birth order might say about us?

One of the researchers I talked to said that people read information about birth order in the way they read horoscopes. Birth-order research does seem to show that a lot of what people arrive at on their own is confirmed by the studies. For example, the tendency is for middle children to be a little more lost, oldest children are more responsible, and younger kids are wild.

Are there rational explanations for these traits?

Older siblings get more total-immersion mentoring with their parents before younger siblings come along. As a result, they get an IQ and linguistic advantage because they are the exclusive focus of their parents’ attention. The idea of what businesses call “sunk costs” comes into play here, which means that by the time an older child is 2 or 3 years old, the parents have sunk a great deal of money, time, and physical and emotional energy into them. When a younger child comes along, evolutionarily speaking, it’s like a product that is not as far down the creation and assembly process. So, you put more energy into the product that is further along because that one has the greatest chance of success to thrive in life. There is a lot of parental focus on the older child, even if they’re not aware they’re doing it.

The youngest child has a valedictory quality because he or she is the parents’ final shot. Youngest kids tend to develop a greater ability to use low-power strategies, like getting inside the minds of and charming other people, because they’re the smallest child in the house. When you can’t thump your older siblings to get what you need, you learn to disarm them by being funny, or you learn to have a better intuitive sense. The biggest advantage a youngest child gets that middle children do not is to eventually become an only child. They get to experience the uniqueness of being the focus of parents’ attention that the firstborn had, if only for a little while, because they’re the last one left in the house. The middle child gets none of this. That’s why they tend to invest in greater ways in friendships outside the home and be much less connected to the family.

There are a growing number of unconventional families these days -- with lots of stepparents and stepbrothers and sisters. How is this impacting sibling relationships?

Blended families are much more common than they used to be, and that’s changing sibling relationships, since more kids are experiencing them. With blended families you can get explosions of the traditional birth-order sequence, which can be very disorienting, but also educational, for kids. A firstborn child who is used to being the prince of the family can be knocked down to second or third. The baby of the family might be used to coddling and indulgence, but when a younger kid comes along, it can put them in the middle, which can be an unremarkable position. Relationships with step-siblings tend to be more fraught in some ways because you’re competing more for parental attention, and there is a lot of territoriality that goes along.

On the other hand, if blended families survive beyond the benchmark of six years, the relationships between step-siblings are often as intimate and enduring as the ones between full siblings. In some ways they can be better because they’re devoid of that biological competition for parental attention. A lot of this depends on how long the kids are in the house. If you’re 14 years old when your mom gets remarried, you don’t get six years with the members of your step-family. The younger the kids are when families blend, the better they do, because they have more time together and they resent the stepparent less. In this respect, the research is a moving target because we’re seeing all kinds of radical changes in families that may take time to see exactly how they affect sibling relationships.

What conflicts cause the most problems for siblings?

Property is the biggest one. With very young kids, when researchers look at what the causes of fights are, some 80 percent of all fights in the playroom break out over property disputes. It’s a "my toy, not his toy" issue, which is an easy one for parents to identify and resolve. Once you figure out whose toy it is, you have a nice lesson in sharing and in respecting other people’s property. Parents shouldn’t just roll their eyes, even though conflicts over sharing are so common, because property for a small child is a critical way of establishing authority and control over a world in which they have virtually no power. You’re physically little. You don’t have any resources beyond what your parents can and are willing to give you. So, when something is yours, it becomes a real totem of the little bit of authority you have, which is one of the reasons little kids are so terrible about sharing.

There is a prevailing idea that divorce is really bad for children, but you talk about ways family conflict can actually be good for siblings’ relationships.

This is one of the things that drove me to write the book. My parents were divorced, and my mother was divorced twice. Each time we came through it, my brothers and my relationships seemed to be annealed in some way. They were strengthened. If you begin with relatively strong sibling bonds, divorce is like any other any crisis in that the people involved tend to pull together. When your parents, who are the anchors you’re counting on the most, are falling down on the job, siblings look to each other and find way to pull together, because the last thing you can afford to see fractured at that point is the unit among yourselves.

Paradoxically, siblings also tend to pull together in situations in which any of the kids are battered, particularly if there is one target child. Parental abuse tends to rupture the ties between parent and child, so kids who survive terrible situations like that often end up much closer to their siblings. Older children especially tend to side with the abused younger sibling over the abusive parent.

What happens to sibling relationships when a parent dies?

The loss of a parent can draw kids closer together. In fact, if a parent dies, older siblings will quickly jump into that breach to become caretakers and gentle disciplinarians. Sometimes parents have to instruct an older child to fill in and help encourage the younger siblings to clean up their room or do their homework, but often that isn’t necessary. The older children fall into that naturally, and the younger children tumble into that relationship very comfortably, because who could be safer than someone you already know and trust?

Why do single children get a bad rap?

In the early 20th century, some scientists said things like being an only child is a disease and the world would be better if only children didn’t exist. The idea was that only children learn self-absorption and selfishness when they should learn sharing. They learn entitlement when they should learn earned favors. When you think of an only child, the stereotypical image that comes to mind is of a forlorn figure in a silent house whose parents are occupied by adult chores and who doesn’t know how to play with cousins at Thanksgiving. Yet study after study has found that none of this is true.

Only children tend to exceed other kids in terms of academic accomplishments, sophistication, vocabulary, and often, social skills as well. They have a great ability to make and maintain friends, and to resolve conflict, because they have to be nimble about learning skills outside the home, like in daycare, play groups, and school. One of the advantages of being an only child in the home is that the conversations you hear and participate in, the TV shows you watch, and the vacations you go on tend to skew older. All these things become food for the developing brain, and by the time the child is in first grade, he or she has a background in adult thinking and abstract concepts that children with siblings just don’t get.

In each chapter there are gems of advice for parents, and one is that treating children equally is a bad idea. 

You can’t treat your children equally, because they’re very different people and they have different needs. Age is the obvious driver of this, because older children will get certain privileges and freedoms that younger kids don’t get, and younger kids will get indulgences that older children won’t get. But if your older child is a natural student and your younger student is a natural artist or athlete, you’ve got to look early at what the aptitudes are -- not only to support them but also to celebrate them. It’s important to understand that kids will often de-identify from their older siblings. Kids grow like leaves in that they look for the places where there is a spot of sunlight and shift into that space instead of growing directly under the other leaves that are shading the spot above them. Parents have to be aware that it is critical for kids to find their niche in the family as the smart one, the pretty one, the funny one or the athlete. To try to hammer kids into the same mold is a mistake. All kids find their way to say, “This is how I stand out,” and parents have to respect that.

By Mandy Van Deven

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