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Birth Order Theory

This guide is designed as an introduction to researching the topic of birth order and understanding how it might affect your life and relationships.

What is Birth Order?

Birth order refers to the chronological order of sibling births in a family (first-born) (second-born), etc.

A researcher named Alfred Adler developed birth order theory in the 20th century. The theory claims that the order in which a child is born shapes their development and personality. 

Today, many psychologists believe that where you fall in your family’s birth order has a major impact on your personality development.


Additional Information

Being the first, middle, youngest, or only child probably influences your behavior.

Here's what you need to know about the link between birth order and personality traits.

Psychologists believe the secret to sibling personality differences lies in birth order—whether you're the oldest, middle, youngest, or only child—and how parents treat their child because of it.

Firstborn Personality Traits

Firstborns bask in their parents' presence, which may explain why they sometimes act like mini-adults. They're also diligent and want to excel at everything they do. As the leader of the pack, firstborns often tend to be:

  • Reliable
  • Conscientious
  • Structured
  • Cautious
  • Controlling
  • Achievers

Middle Child Personality Traits

Parents might raise their second-born with less of an iron first due to their previous experience. They might also be less attentive since there's other children in their lives. Therefore, the middle child is often a people-pleaser due to the lack of attention they get in comparison to older siblings and younger siblings. In general, middle children tend to possess the following birth order personality traits:

  • People-pleasers
  • Somewhat rebellious
  • Thrives on friendships
  • Has large social circle
  • Peacemaker

Youngest children tend to be the most free-spirited due to their parents' increasingly laissez-faire attitude towards parenting the second (or third, or fourth, or fifth...) time around. The baby of the family tends to have the following birth order traits:

  • Fun-loving
  • Uncomplicated
  • Manipulative
  • Outgoing
  • Attention-seeker
  • Self-centered

Parents Magazine: Birth Order Traits by Jocelyn Voo

Your birth order and family size may have an impact on your heart health. A new Swedish study found that first-born children had a lower risk of heart attacks and strokes than their younger brothers and sisters. But having many siblings was associated with an increased risk of such cardiovascular events.

For the study, the authors accessed data on more than 2.6 million adults born between 1932 and 1960. The study participants were between the ages of 30 and 58 in 1990.

The researchers also gathered data from national registers on fatal and nonfatal heart problems and strokes that happened over the next 25 years.

Overall, the investigators found that first-borns had a lower risk of nonfatal cardiovascular and coronary events than siblings born later.

But first-born men had a higher risk of death than second- and third-born siblings, while first-born women had a higher risk of death than second-born siblings, but equal to further siblings.

Compared with men with no siblings, men with one or two siblings had a lower risk of heart attack and stroke, while those with four or more siblings had a higher risk. Also, compared with men who had no siblings, men with more than one sibling had a lower risk of death, while those with three or more siblings had an increased risk of coronary events. That pattern was reflected in women as well.

The researchers considered relevant factors such as income, obesity, diabetes and alcoholism, but did not have information on diagnostic procedures or lifestyle behaviors like smoking and diet, which is a study limitation.

Because this was an observational study, it can show an association, but not cause and effect, the study authors added.

U.S. News & World Report (Source: BMJ Open, May 25, 2021)

Because only children spend so much time alone, they're self-entertainers and often tend to be the most creative of all birth orders. In fact, Leman calls only children "Super Firstborns." Like oldest siblings, they are confident, well spoken, pay enormous attention to detail, and tend to do well in school. Plus, spending so much time around grown-ups often makes onlies act like "little adults." 

Only children have never had to compete for their parents' attention or share toys with their siblings, so they do run the risk of developing a self-centered streak. They're also used to feeling important and may have a hard time when things don't necessarily go their way, Leman says. Because their role models are competent adults, onlies are even more susceptible to perfectionism than firstborns.

Parents Magazine: What to Know About Older, Younger, and the Middle Child Personalities by Natalie Lorenzi

Parent's birth order experiences powerfully impact their relationship with their children. They often explain why parents treat each of their children differently. A parent may unconsciously identify with a child of the same birth order position because the child reminds her of herself, and she understands the child’s experience. 

It’s interesting to note that a parent's identification with their child can raise more affection and protectiveness sometimes, while at other times it can work conversely. 

Bringing all these early birth order experiences into awareness and working with them carefully is key for helping parents respond more objectively and raise their children to feel equally loved. Here are some strategies that can help:

Self-analysis is of major importance. It is crucial for you as a parent to examine birth order experiences in your own family and bring any resolved issues to awareness.

Observe your emotions. When you find yourself getting extremely upset by a child's behavior, such as your younger child taking your older child's things, try to slow down and take stock before you react. 

Calm down. When things heat up, take a deep breath, count to 10, or walk out of the room for a few moments to gain your composure.

Learn about birth order experiences in each spot in the birth order. Birth order experiences including sibling battles, competition, gender, the size of the family, and the age gap can affect a child's reaction. Understanding all the facets of these experiences will help you communicate in a way that helps each child feel self-confident and equally loved.

Psychology Today: How Parental Birth Order Affects Parenting by Meri Wallace

Many birth order experts agree that twins tend to organize themselves according to their overall place within the family.

 For example, if they have one older sibling, they will both exhibit characteristics of a second born. If they are the oldest, they will adopt some traits of firstborns. 

Twins often exchange dominance throughout their lives, and in that sense may alternate between birth order categories.

Aside from inherent personality traits, the impact of birth order in multiples is likely more often one of perception rather than reality, especially in light of recent studies. Parents of multiples, as well as society, apply behavioral expectations based on traditional birth order characteristics; in reaction, the individual children behave in fulfillment of those expectations.

Parents of multiples have a vital responsibility to foster their children's individual personalities outside of the realm of birth order. To accomplish this, they can do the following:

  • Adopt a consistent, neutral set of expectations that will allow each child to fulfill his or her inherent personality
  • Avoid birth order stereotypes
  • Downplay the significance of birth order; if necessary, choose not to identify the multiples' birth order
  • Discourage others, including extended family, teachers, and curious strangers, from overemphasizing birth order importance


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