What Is Birth Order Theory?

If you have siblings, have you ever wondered why your personalities vary so much? Would you describe yourself as a “Type-A” personality who tends to take charge, while your younger sibling may be more of a free spirit (much to your chagrin)?

Those personality traits may have something to do with the order in which you and your siblings are born. Birth order theory explores how someone’s identity can be influenced by whether they’re the oldest, youngest or middle child.

“The general concept of birth order theory is that where in the family the child is born is going to predict or determine what their personality style is like,” explains psychologist Kate Eshleman, PsyD.

Birth order theory isn’t necessarily a new concept. During the early 1900s, psychoanalyst Alfred Adler detailed the idea of birth order theory and the attributes assigned to each of those placements in the sibling lineup.

And while it’s a fascinating concept to debate with your brothers and sisters over the holidays, it’s just one part of your personality pie.

“There’s a lot of factors that contribute to our personality and its development and maintenance over time,” notes Dr. Eshleman. “Some of that is where you’re born, but also genetics, life experience and how you were parented.”

It’s also important to note that while there’s been research around birth order theory, there isn’t an official medical or psychological diagnosis when it comes to birth order and other ideas around “oldest child syndrome,” “eldest daughter syndrome” or “youngest child syndrome.”

Dr. Eshleman takes us through each birth order and explains what kind of personality or behavioral patterns you may notice in yourself and others.

Oldest child syndrome

If you’re the first-born sibling in your family, you may experience oldest child syndrome (also known as first-born syndrome and closely related to eldest daughter syndrome). While being the oldest has some upsides (for example, your parent’s undivided attention or being the first to go to school), you may also have to deal with the high expectations placed on you.

Oldest children tend to have the following characteristics or be described as:

• Responsible.
• Competitive.
• Confident.
• Well-behaved.
• Bossy.
• Stubborn.
• Intelligent.
• Ambitious.
• Successful.
• A leader.
• A perfectionist.
• Type-A personality.

“A lot of times, the oldest child is described as bright, intelligent and a leader who is very conscientious. They may be a perfectionist, who can sometimes be a little bossy,” shares Dr. Eshleman. “They’re someone whose likely going to be successful.”

In fact, research shows that oldest children may have some cognitive development advantages such as verbal development (learning to speak), quantitative numbers (learning to count) and reading and literacy skills.

“The time and attention that parents give early on to their oldest child promotes that early academic development,” she adds. “Younger siblings might not have that, but while they may not be receiving attention from parents, they’re often getting it from their siblings.”

Youngest child syndrome

If you’re the baby of the family, you’re the youngest child and sibling. You may view your older siblings as competition — trying to outdo or one-up them. Another consideration is how involved or disciplined your parents are. Parents tend to be more hands-off and less strict with their youngest child.

Those who are the youngest child tend to have the following characteristics or be described as:

• Outgoing.
• Social.
• Rebellious.
• Spoiled.
• Carefree.
• An attention-seeker.
• A free thinker.

“A lot of times, the youngest child can be described as very social, outgoing, fun-loving and maybe cares a little bit less about performance and some of those perfectionistic tendencies,” explains Dr. Eshleman. “But they may be an attention-seeker.”

Middle child stereotypes

As the middle child, your personality and what traits you exhibit may have a correlation to the traits your older sibling has. For example, if the oldest child in the family is a rule-follower and a perfectionist, as the middle child you may choose to rebel and break the rules.

And you may harbor some resentment that your oldest sibling has privileges and opportunities you don’t have, while your youngest sibling seems to get away with everything and tends to have less responsibility.

Those who are a middle child tend to have the following characteristics or be described as:

• Independent.
• Diplomatic.
• Agreeable.
• Realistic.
• A negotiator.

“Oftentimes, middle child traits include being a moderator or the peacekeeper,” says Dr. Eshleman. “They may be seen as independent because they may feel like they must be. They also tend to go with the flow and may seek their own attention.”

Only-child traits

No siblings? If you’re an only child, you may think birth order theory doesn’t apply to you. But consider how not having to compete for your parents’ attention may give you confidence. An only child, who doesn’t have to learn how to share with siblings, may have a hard time if they don’t get their way.

If you’re an only child, you may have the following qualities:

• Creative.
• Confident.
• Mature.
• Well-spoken.
• Detail-oriented.
• Perfectionist.
• Self-centered.
• Self-entertainer.

“Ultimately, you end up having some of the attributes of the other birth orders, but oftentimes, you’re much more like an oldest child,” says Dr. Eshleman. “You may be described as more mature, having some leadership abilities, more conscientious and maybe a perfectionist. An only child may be competitive with others.”

Does your birth order cause issues in adulthood?

As with many things, the answer is complicated. While your birth order can play a role in your personality and relationships, other factors like your sex, life experiences and the age differences between siblings can contribute to the type of person you are.

“You develop these personality styles, but they can change over time,” clarifies Dr. Eshleman. “How our personality shines through and how we interact with others also determines how others interact with us. If we have this natural interaction style, people are going to tend to respond to that, which also helps maintain it. But overall, personality style can shift and change over time.”

Your mental health may be impacted positively or negatively based on your birth order. For example, being the oldest child who has a lot of responsibility placed on them as they grow up may result in you feeling like you didn’t get a “proper childhood” and can lead to anxiety or depression.

What to do for your child

How you parent your child can play a role on the type of personality and behavioral traits they develop. Dr. Eshleman offers the following suggestions:

• Consider where you are. If you’re a first-time parent, you may be overprotective with your first child. “When we think about parents and they have their first child, parents are more anxious. They want to do things right,” says Dr. Eshleman. “They may have more time on their hands to focus on the first child. They’re younger by nature, too. So, there’s a lot of things that are happening when a first child is born, versus when any subsequent children are born.”
• Give yourself grace. You may parent your oldest child differently than you do your youngest. “We learn over time that they’re not breakable,” she says. “You start to learn that if they fall down, they get back up. They’re not quite as fragile as you thought. You learn that maybe they don’t need as much care, which changes our parenting style as well.”
• Appreciate your child. As a parent, you want to think about the expectations and responsibilities you place on your child. Another important aspect? Respect who your child is. “The goal is to parent the child that you have. So, while people aren’t necessarily born with personalities, we’re born with temperaments that start from an early age. Ideally, you’re parenting the child you have and responding to their needs,” notes Dr. Eshleman.
• Know there will be differences. “Every opportunity for every child, even within a family isn’t going to be the same,” she states. “But the goal would be to give all of your children similar opportunities to try to avoid any of those stereotypes or that sibling rivalry.”

While it can be fun to consider birth order theory and how it impacts your own personality or those of your siblings or own children, Dr. Eshleman says we should take all of these views with a grain of salt.

“Talking about birth order theory can lead to great conversations,” she continues. “It can enforce the idea of confirmation bias and how we look at our own families. You may think that the oldest totally fits the characteristics of an older sibling. But if we step back and look at the literature, ultimately, there is nothing to determine that birth order is entirely accurate.”