“Middle child syndrome” is not a medical diagnosis. Instead, it is an informal term that some people use to describe the way that a person’s position within their family has affected their personality.

The concept of middle child syndrome comes from the idea that birth order affects how children develop. Although this makes intuitive sense, and some older studies suggest a link, newer research often fails to find any strong correlation between birth order and personality.

However, some people may feel as though the way a parent or caregiver treated them in comparison with their siblings has affected their personality or mental health. These feelings are valid and may influence a person’s well-being and relationships.

For example, a middle child might feel as though their parents or caregivers paid more attention to their older or younger sibling, resulting in them feeling overlooked or misunderstood.

Read on to learn more about middle child syndrome.

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Middle child syndrome is an informal term that refers to the way birth order has affected a person’s personality or mental health.

The idea comes from the theory that middle children share similar experiences, resulting in similar challenges. This supposedly affects their personality, relationships, and, potentially, their behavior in adulthood.

However, because it is an informal term, there is no set definition. The meaning of middle child syndrome and the difficulties it causes vary from source to source. People may use it to refer to a wide range of experiences, which might be contradictory and inconsistent.

In general, some of the suggested effects of being a middle child include:

  • Feeling ignored: Middle children may feel that older children get more attention or that caregivers cherish the youngest child as the “baby” of the family. This leaves the middle child with a less clear role and, possibly, less parental attention.
  • Social skills and mediating conflict: Some middle children may mediate conflicts between their older and younger siblings, resulting in good social skills or high emotional intelligence.
  • Feeling left out: Some middle children report that they do not fit in well with the family culture.

The idea that birth order affects child development has existed since the beginning of psychology. However, it was psychologist Alfred Adler who proposed that birth order significantly affects personality and experience.

Adler believed that birth order leads children across similar families to face similar benefits and drawbacks.

However, according to the American Psychological Association (APA), there is no strong research to support the idea that birth order affects personality or experience in predictable ways. Other factors, such as socioeconomic status and parenting style, may play a more important role.

It is possible that birth order may indirectly influence personality or have subtle influences, though. For example, parents or caregivers might have less time to spend with their children as they get busier, so their parenting style may have shifted by the time middle or younger children arrive.

There is no scientific support for the notion of a distinct middle child syndrome. Research has not tested for its existence, likely because it is not a well-defined syndrome and has some flaws as a concept.

For example, middle child syndrome relies on the idea of the “nuclear family,” which assumes that people have two parents and that siblings are all alive and of a similar age. It does not consider the influence of step-siblings, half-siblings, or siblings who have significant age differences.

Researchers have tested the role of birth order more generally in personality and behavior, though. While some older studies find a correlation, most recent studies do not find a strong link.

For example, a 2019 study drew on three different data sources to assess the role of birth order in risk-taking:

  • a self-report questionnaire in the German Socio-Economic Panel
  • the Basel-Berlin Risk Study, which measured 39 components of risk-taking
  • a qualitative analysis of birth order in becoming an explorer or revolutionary

The researchers found no correlation between birth order and risk-taking. This finding undermines one birth order theory, which argues that youngest children are often more ambitious.

A large 2015 study also found that although eldest children tended to have higher intelligence scores, birth order did not affect people’s levels of:

  • imagination
  • extraversion
  • emotional stability
  • conscientiousness
  • agreeableness

A 2016 study suggests that birth order may affect prosocial behavior, which is behavior that benefits others, such as kindness. The study found that later children exhibited more prosocial behavior than older siblings.

However, this study only included females, the majority of whom were from middle-class to upper-middle-class households with two parents. This could mean that the results do not reflect the experiences of more diverse populations.

People who believe in middle child syndrome often identify similar characteristics. They typically think that middle children:

  • feel inferior to other children in the family, potentially affecting self-esteem in adulthood
  • are more independent and, therefore, move out of the family home at a younger age
  • have good social skills because they must navigate relationships with the oldest child and the youngest child
  • have good negotiation and conflict management skills
  • feel alienated within their family and may want to spend less time with their family than their siblings do
  • have a more stable temperament and are more easygoing than their siblings
  • find it difficult to know their role in their family

These traits are amorphous, and many people share them. There is no evidence that they are more prevalent among middle children than they are among younger or older children.

Just as there is no compelling research to support middle child syndrome in children, there is no evidence that being a middle child reliably affects adults in any specific or consistent way.

For example, a 2020 study found that birth order directly influenced neither the amount of status the participants attained as adults nor the type of career they pursued.

The authors state that birth order may have an indirect influence on intelligence and educational attainment, which may, in turn, affect a person’s career. However, this is a theory, and more research is necessary to confirm it.

The APA reports that even if birth order influences personality, it is likely less important than other factors. Some other factors that may influence upbringing include:

  • Family relationships: How a person relates to their siblings during childhood and adulthood is likely important. For example, conflict with one specific sibling may be more influential than the person’s position in the family.
  • Parenting style: Whether caregivers are authoritative or permissive, abusive or compassionate, or involved or absent can all affect child psychology.
  • Individual biology: A child’s genetic makeup, hormonal changes, and developmental experiences may affect personality more than birth order.
  • Individual environment: A child’s environment extends beyond their family and includes their friendship group, school, and hobbies. As the child gets older, it may also include romantic relationships and a job.
  • Cultural background: Different cultures have different expectations of children with regard to their age and gender. There are many ways in which this could affect a person’s upbringing. For example, a family that views their firstborn as the most important may place more pressure on them to succeed.
  • Socioeconomic status: Socioeconomic status strongly correlates with many outcomes and experiences. For example, parents or caregivers may have more or less money by the time they have a middle child. This could influence the child’s experiences.
  • Adverse experiences: Adverse experiences can affect children, with the effects potentially lasting into adulthood. Sometimes, birth order influences these experiences. For example, an older child who has moved out of the home might experience less abuse than younger children face, or they might take on a protective role and experience more abuse as a result.

Many factors can affect a person’s role within their family and their relationships with their caregivers and siblings. For some, birth order is one of these factors. However, the concept of middle child syndrome is not medically proven.

In fact, no recent studies have found any strong correlation between birth order and specific personality traits. Some older studies do, but the results vary.

Everyone’s experience of being a middle child is different. This may help explain why researchers have not found reliable scientific support for the notion of middle child syndrome. Although birth order is an important factor for some people, the interplay of other factors — such as socioeconomic status, parenting style, and sibling relationships — is also key.

People who feel as though being a middle child has had a negative effect on them can look to therapy for help and support. They can attend the sessions individually or use them to resolve conflicts between family members.