Contrary to what some popular psychology books tell us, birth order is not destiny. All first-borns are not fated to be president of a big company. Youngests don’t necessarily become the family free spirits and artists. The order in which we enter our family is, however, one of the many factors that shape us into who we are. The family, whatever the family make-up, is our first society. It is the place where we learn about what we can expect of other people and what others expect of us.

Anything we learn early and that is repeated often, whether a language, a belief, a role, or a way to do something, has enormous staying power. (You probably remember a TV theme song from a show you watched every night when you were eight better than you remember what you ate for dinner yesterday.) The early lessons we learn about our place in the social order of our families are thus very powerful.

It’s true that every child brings personality and temperament to the equation but it is interactions with others that strengthen some traits and banish others. Each day, many times a day, babies and young children are shown what will get them rewarded with smiles and an extra cookie, and what will make the big people upset and rejecting. Intelligent little creatures that they are, the kids soon start repeating what sets them apart in the crowd so that they get the attention they need from those around them.

Because families in cultures share some stated values, they generally have some shared ideas about the right way to raise children (even if they don’t actually succeed at it). Stories, songs, plays (as well as TV shows and movies) of each culture support a common idea of the importance of family and the value of certain roles. The result is that children in these families come to some similar conclusions.

In middle American culture in which there is a strong value on education and achievement, first-borns and only children often become achievers; second-borns tend to rebel against the pressure to succeed in academics or business but find success in being socially capable; babies develop skills in charm and getting others to do things for them. In larger families, kids have more room to go their own ways and to develop their own abilities. Because the parents’ attention is spread thinner, kids in very big families either learn to rely on each other or, conversely, become super-competitive for what attention is available. All of these personal styles, though different, are nonetheless in the service of becoming successful in life.

Remember that it is not the birth order itself that determines a child’s personality but rather how that child interprets his situation and how the rest of the family rewards or rejects what he makes of it. But because there are cultural similarities among children born in the same position, knowing them does give students of people a place to start when trying to understand what makes a person who he or she is.

Why Each Sibling Grows Up in a Different Family

For most families, the arrival of the firstborn is a big event. It changes people into parents. It changes a couple into a family. For single moms, a baby changes her from being a single to being a single parent family. The first child therefore usually gets more focus and fuss than those further down the line. He spends most of his early life with grownups as his models for human behavior. Pleasing them by being like them usually is the ticket for getting what he wants and needs so he figures out what they like and does it.

Each succeeding child enters a different, larger, more complicated family. The second-born has a bigger and more capable older brother or sister to deal with. The family of three has now become four. Parents, whether delighted or dismayed by the arrival of number two, tend to be more stretched. That second kid takes a look at the scene and figures that the first one has already cornered the market on certain skills and traits. He knows he can’t compete. That other kid is bigger and has a head start. If he is to be seen and fussed over, he’d better come up with something else. The most obvious answer, especially if the kids are the same gender, is to be the opposite of number one. Being a different gender makes number two’s job easier because difference and specialness is built in.

With the arrival of a third, the kids now outnumber the adults. One adult has only two hands, making it more difficult for one parent to manage the kids. Number three now has not one, but two bigger, more capable kids in his life. The challenge of finding a unique role and getting a piece of the attention pie has become more complicated — and more subtle. “Hmm,” thinks this little one, “Role X is taken. The opposite is taken. How can I find a place?” Often they opt out of the competition going on between one and two and find yet another way to assert themselves. And so on, and so on. Each child has a more complicated job to get the attention he needs and assert his individuality.

Other Factors That Influence Development

Other factors are at play too. Each child enters at a different spot in the timeline of the family. Parents get older, sometimes wiser, sometimes more or less stressed. The economics of the family may change for better or worse. There may be more or less extended family around to help out. Some families favor one gender over the other. Sometimes there is mysterious favoritism for one child over the others. Sad events like a serious illness, substance abuse, or family violence, and celebratory events like a move to a more spacious home, sudden improvement of family finances, or a chance to go to a better school all also affect the developing personality of our children.

None of the choices kids make is conscious, of course. Initially kids are simply reacting to the people and the situation around them. A child needs to be noticed and to be taken care of. Some kind of uniqueness is what engages other members of the family and guarantees a spot. One of our inborn survival skills is an acute power of observation. As the other people in the family react to the children’s reactions, the kids figure out what works and what doesn’t.

The following is only one example of how the situation and therefore the possibilities for each child might change in a middle American family.

John and Jane Doe have been married for three years, following a four-year courtship. Even though they are struggling financially and are living in a tiny apartment, they really want a child and are delighted when their son arrives. Both have jobs but they are lucky that John’s mother lives nearby and is happy to provide daycare.

This couple has read all the books. They read to little Johnny Jr. They play classical music. Grandma isn’t the type to actively play with him but she spends hours cuddled up with him, doing puzzles and reading books. By the time he is 3, he knows his numbers and alphabet. The household is quiet and organized. Johnny figures out that the way to belong in this family is to be quiet, to enjoy learning, and, because grandma is older and both parents are so busy, to be independent in his play.

Enter little brother Mikey. The family is doing better financially and moves into a house in a neighborhood with lots of kids. Dad works long hours during the week but is committed to giving the boys lots of his time on weekends. Mom has a job in a family-friendly company. After an eight-week maternity leave, she enrolls both kids in the company’s daycare. Grandma visits often and continues her special relationship with John Jr.

What is the most obvious place for Mikey? He’s used to competing with other babies for time and attention at daycare so a good guess is that he will be noisier and rowdier. He may decide that big brother has the academic world wrapped up so he will assert his uniqueness by being more social and more capable in rough-and-tumble play with other kids. If, however, the family places a very high value on academics, he may assert his uniqueness by letting his brother be the star in one area while he excels in another. (It’s not at all uncommon to find families where there is one historian and one mathematician. I do know of one family where all four kids became doctors but each has his or her own specialty.)

Enter the third-born, this time a girl named Barbie. Mikey feels squeezed. He doesn’t get the special privileges of being the oldest, nor does he get the special attention for being the cute baby girl. The boys have to share a room for the first time. Being so different, it’s hard for them to get along. Both are mad that this little interloper has made life more difficult.

Meanwhile, Barbie has two older, more capable guys ahead of her. Since she can’t be as big or as strong, she must develop other ways to be noticed. She may assert her individuality by becoming a girly-girl or, equally likely, she may take them on and become the most demanding and assertive of the group.

Why Study Birth Order?

Sometimes it is very helpful to understand some of the principles that have influenced our lives. We can’t change the past, it’s true. But we can change the way we look at our past and the way we think about our future. Knowing (and perhaps sharing) more about birth order traits and how a person’s role in his or her family always makes a kind of sense gives us a sympathetic way to understand ourselves and our siblings. If we’re unhappy with our own family drama, this may give us a way to talk about it that is interesting and non-blaming. When people feel understood, there is more room for change.