Could Your Birth Order Determine Your Personality Type?

Clinically Reviewed by Steven Melendy, PsyD. on July 11, 2016

Anecdotally, almost every parent has noticed the personality differences that arise in their children. How is it that Rachel, the firstborn, seems to have such different personality characteristics than her younger brother, raised in the same house by the same parents just two years apart?

Alfred Adler, an Austrian psychotherapist, was the first researcher to study these natural differences. He believed that our birth order within a family played a significant role in the type of adult we would become. Firstborns were observed to be goal-oriented and perfectionists, for example, whereas their younger siblings were judged to be more affectionate, socially oriented and carefree.

But it is not necessarily the case that a firstborn drops out of his mother's womb with all the characteristics of a leader.

In 1953, a researcher called Rudolf Dreikurs noticed that, in practice, parents never treat two children alike but rather behave very differently towards each child depending on their position in the family hierarchy. So if the firstborn has leadership qualities, it's because his parents treated him as the apple of their eyes - and this influence shaped the child's attitude and behavior.

The Birth Order Hypothesis

Here's what birth order advocates have to say about personality characteristics, by reference to a person's position within the family - plus a little speculation as to how Adler's observations might translate to Myers and Briggs' theory of personality types.


Firstborns are rule-abiding overachievers who respect and trust authority. They often appear as perfectionists, are academically more successful than their younger siblings, and are typically judged as more serious, seclusive and cautious than later borns. Adler describes them as:

  • Conscientious
  • Reliable
  • Disciplined
  • Independent
  • Seclusive
  • Achievement-oriented

Mapping this to personality types, we would expect older siblings to have a greater probability of having an Introverted, Thinking and Judging personality. Parents typically set more stringent standards for their firstborns, which means that firstborn children are more likely to be willing to work hard to please their parents, developing the characteristics of a structured, reliable achiever.

Middle Children

Caught between the oldest and the youngest, the middle child often has trouble finding her place in the family and may lose her sense of self. Middles excel at peacekeeping and are generally judged to be non-confrontational, non-competitive, diplomatic and compromising. Adler describes them as:

  • Sociable
  • People-oriented
  • Nurturing
  • Easygoing
  • Loyal
  • Independent

From these observed characteristics, we speculate that middle children would prefer Perceiving to Judging and Feeling to Thinking. Perceivers seek to understand life rather than control it, and are generally even-tempered and flexible. Feelers, like middle children, appreciate harmony, sensibility and human relationships.


The baby of the family tends to be the most idealistic and free-spirited due to their parents' increasingly relaxed attitude towards parenting the second (third, fourth) time around. They are judged to be more popular, more affectionate and more persuasive than their older siblings. Adler describes last-borns as:

  • Outgoing
  • Agreeable
  • Spontaneous
  • Adventurous
  • Affectionate
  • Manipulative (to attract their parent's attention)

Similar to middle children, we would expect younger siblings to exhibit a preference for Feeling and Perceiving over Thinking and Judging. As the most outgoing of the bunch, we might also expect them to score highly as Extraverts. Extraverted Perceiving types tend to live in a particularly flexible and spontaneous way, preferring liberty and adventure to rules and restraints.

What Does the Research Say?

Is there any proof that older children are more likely to be Judgers, or younger children Perceivers, or are we inventing hindsight rationalizations for something that doesn't exist?

Unfortunately, there's no clear answer to this question. Research is scarce, and what little there is uses such small sample sizes that it is difficult to draw any real conclusions.

The primary study, published in The Family Journal: Counseling and Therapy for Couple and Families in 1998, sought to measure the influence of birth order and other factors on the Myers-Briggs dimensions of Introversion/Extraversion and Judging/Perceiving for 144 study participants. Known as the "attitude" scales, I/E and J/P preferences determine how a person orients with the world and communicates with the people around them. According to the researchers, a person's preference on these scales is likely to be influenced by parenting style and, therefore, birth order, whereas a person's preference on the mental activity (S/N) and decision-making (T/F) scales are not.

The researchers identified parenting style as having a significant main effect on both the Extraversion and Judging functions. Firstborns had significantly higher Introversion and Judging scores than did middleborns and last-borns. The more authoritarian the parenting style, the greater the I and J score.

Conversely, more middleborns and last-borns had higher mean scores on the Extraversion and Perceiving scales - consistent with Adler's findings.

So What Does It All Mean?

Personality is not a fixed list of attributes, but instead is a complex interaction of attributes that depend on the situation we find ourselves in. It may be that birth order stereotypes hold true in the home, while we are children. But away from parental and sibling influence, other variables may come into play.

Modern research suggests that Adlerian birth order theories may be too simple. More recently, scientists have been examining the role of other influences on personality, such as gender, genetics, age spacing and socioeconomic factors. Birth order is just one lurking variable among many.

The bottom line is, no one really knows the impact that birth order has on personality type, and there's a desperate need for research.

Until then, the birth order mystery remains unresolved.

Molly Owens

Molly Owens is the founder and CEO of Truity. She is a graduate of UC Berkeley and holds a master's degree in counseling psychology. She began working with personality assessments in 2006, and in 2012 founded Truity with the goal of making robust, scientifically validated assessments more accessible and user-friendly.

Molly is an ENTP and lives in the San Francisco Bay Area, where she enjoys elaborate cooking projects, murder mysteries, and exploring with her husband and son.

More from this author...
About the Clinical Reviewer

Steven Melendy, PsyD., is a Clinical Psychologist who received his doctorate from The Wright Institute in Berkeley, California. He specializes in using evidence-based approaches in his work with individuals and groups. Steve has worked with diverse populations and in variety of a settings, from community clinics to SF General Hospital. He believes strongly in the importance of self-care, good friendships, and humor whenever possible.


kaisheann says...

I am the last in my family. I am a ENTJ.

Guest (not verified) says...

I am the last born and my personality type is INTJ. So this might hold truths in some cases, but not all the time.

Lilivan (not verified) says...

and that prooves anything because......?

Robert Walter (not verified) says...

Yeah...I'm the baby by 12 years & I am an ENFJ.

My mother has Dissociative disorder & bipolar, & one of my older brothers who is 20 years older than me (we all have different dads) lived with us when I was growing up. He has schizophrenia & bipolar. So, I spent much of my youth helping them stay on track & managing things, as well as trying to keep the peace. I don't think I grew up with much of the stereotypical "last child" freedom & Perceiving quality, since I always had to be the responsible one.

I guess the type of family dynamic this article discusses is based on a family where the parents are together & the kids live at home.

Oldest brother 45 y/o - ENTP/ENFP (I think...)
sister 38 y/o - INFJ
middle brother 35 y/o - ISTP
me, youngest brother 25 y/o - ENFJ
Mother is 68 y/o - INFP

Angela McCarthy (not verified) says...

I am the Oldest child and am an ENTJ

Guest (not verified) says...

Oldest and ENTP

LaurenHowie (not verified) says...

I am also an ENTJ, but I am a stereotypical first child. I wonder if there is a pattern for children with no siblings. Do they still take on similar characteristics as first-born children?

Guest (not verified) says...

I have been waiting for forever for the research on adopted children to commence.
When you superimpose a child into a different birth order in their new family, what changes occur?
What happens if you put an only child in slot of seventh born?
Until that is fully researched only then can we wisely state the effects of order on personality.

From experience I can tell you some things remain the same but others do not.

Guest (not verified) says...

I'm the youngest and an ISTJ. Almost none of those adjectives apply to me.

A. (not verified) says...

Me too! It was odd being the factual one when you're the baby and everyone wants you to only be cute, not analytical.

janyaadi says...

Just pointing out that an individual circumstance doesn't prove the study is inaccurate. It's a general finding, not case-specific.

Laura T Dishong (not verified) says...

What about only children?

Leland (not verified) says...

Only children are usually categorized with firstborns and sometimes called "super firstborns" because they demonstrate some of the same tendencies to an even higher degree. (Source: The Birth Order Book by Kevin Leman)

Markus (not verified) says...

I am the Firstborn. I have freed myself from "the mold" and am now a happy 44 years old successful ENFP today :)

Ddalton (not verified) says...

I find this very interesting and humorous actually. I am the oldest of my siblings, and while most peers and superiors think I have strong leadership skills, I am actually the least rigid and most free thinking of my siblings. I happen to be an ENFP which seems to be more likely of a youngest sibling. I was an only child for six years though so growing up there was a large gap between my development and my siblings so that may be a contributing factor. Interesting read!

Sheila Ryan Hara (not verified) says...

As the eldest and only daughter in a white, middle class 1970-80's family, I am INFP. My younger brother often exhibits eldest son characteristics because he is the eldest SON. Gender definitely plays a role. I would say he is ISTJ, and my other two brothers might be, too. We were raised by an authoritarian mother and a distant father in a home environment that was ruled by alcohol.

Raychel (not verified) says...

Although I am the youngest of three sisters, I am an INTJ.

Jill Barlow (not verified) says...

I have always been interested in birth order.... because I am an only child. I have three children, but they do not fall into these spots exactly. I know it's not an exact thing anyway, but it's interesting to me how they really don't.

Jacob Engel (not verified) says...

Hi Molly,

Great topic!

My wife & I are first borns!

While I'm an ENTJ she's an INFP...

Though both of us carry marry of the same traits...

Behaviors aren't necessary only personality types.

Dr David Kiersey in his fantastic book, Please understand me has a great explanation which i find is quite accurate.

That fist born sons take after their mother and first born daughters take after their father. In our case its very accurate.

Your thoughts?


Guest (not verified) says...

Here is where genetics come in to play. That assertion does not follow in all cases. Only in a high % of the times do children possess the traits of the opposite sex parent. And if you follow that through, your parents extol their opposite sex parent. Thus granddaughters are akin to their paternal grandmother and grandsons to their maternal grandfather. The key is that there are exceptions to the rule.

Magreth Nailenge (not verified) says...

I am both a first born (on my mum side) and a middle child (on my dads side, i have two older brothers and four younger siblings) and I am an ENTP.

EV ZYTVELD (not verified) says...

Interesting topic. What about the effect of the 3rd and 4th child born after 8 years from the older siblings? Also in my case, I am #3 and the first boy, #4 was also a boy. My brother and I are about 3 years and 8 months apart. My sisters were about 2 years apart. These are also factors in our upbringing. As I am sure that my father was delighted to have boys after 8 years of having only daughters. It showed in my youth for sure, I was spoiled quite a bit by my sisters and parents, at least till my brother was born.

Jay Rosenberg (not verified) says...

How can baby to be born with a specific personality based on when its born? Personality comes with the baby. Like fingers and toes. Then develops further.
Personality is lifelong, though it broadens out and nibbles at the edges of similar personalities as we get older.
There is proof, though, that personality can skip a generation, like I have my grandfather's personality type, INTJ.
Interesting article for discussion.

Jay Rosenberg (not verified) says...

How can baby to be born with a specific personality based on when its born? Personality comes with the baby. Like fingers and toes. Then develops further.
Personality is lifelong, though it broadens out and nibbles at the edges of similar personalities as we get older.
There is proof, though, that personality can skip a generation, like I have my grandfather's personality type, INTJ.
Interesting article for discussion.

Guest (not verified) says...

Youngest child with an intj personality. My family circumstances had me raising myself at the age of 12, except for the financial aspect.

Kelli hoover (not verified) says...

Only child and definitely a infj.

Lisa L (not verified) says...

First born and ENFP...uh oh. :)

Guest (not verified) says...

What about only children?

Guest (not verified) says...

This runs so true for my family. I'm first born and INTJ, my younger brother is ESFP

Yoo (not verified) says...

Well, this is completely off for my family. Oldest brother is an ESFP, quite the handful he was. Older sister is ISTP.And me and my youngest sibling are INTP. Hard to get anything on the judging function info as we are all perceivers.Sorry mom.Interesting nonetheless.

Guest (not verified) says...

What about an only child?

Judife (not verified) says...

I'm an only child and an INTJ.
I believe it depends on the parents on how they molded their child during childhood, their behavior towards their child with respect to the parents/family financial capability and education. My mother is greedy (streetwise), hard-working and caring. My father is faithful, disciplinarian and hypocrite to societal views. Both of them are controlling, this probably influence the INTJ personality of me.

Curious (not verified) says...

(For the Author)
How do you think these theories would apply for only children? Same as with the eldest-born, or different dynamics?

Guest (not verified) says...

Middle child and INTJ

Guest (not verified) says...

Middle child, but live as only child most of the time. INTJ

Sophie413 (not verified) says...

I am an INFP and firstborn. I actually might say that as far as parenting styles, children tend to do the opposite of what their parents teach. Like, my parents had a very STJ authoritarian parenting style, so I rebelled and developed my (very strong) NFP characteristics. I see this happen with a lot of people. I have a friend whose parents let her roam free and never really worried about her, and now as a parent, she is extremely overprotective.

Corky (not verified) says...

I am a first born of two constantly hypercritical parents. My next sister (5 years younger) has now become "the oldest" and the 3rd born is now the middle (10 years younger) I spent most of my life wondering why I could not be the typical firstborn and then listening to a Kevin Lehman show found out when he explained what shifting can happen in a family. I helped raise my 2 younger sisters and now you might say they are raising me. Life is easier now - I am easier on and with myself now - and people in general are more comfortable with me (undoubtedly because I am) I've forgotten my Myers-Briggs score but have a feeling that it could be different were I to take it now. Thanks for the good article, I'm sure it will help many

Guest (not verified) says...

This certainly seems to fit for my family...

Oldest- intj
Middle 1 - infp
Middle 2 - infp
Youngest - esfj

coby (not verified) says...

if this doesn't describe my husband, the eldest with two sisters, i'll eat a hat. but what about onlies?

Jessicataylor333 says...

Me: Middle Child - INTJ
Firstborn Sister - ENFJ
Youngest Brother - INFJ

Leland (not verified) says...

My family doesn't really follow this...

Oldest: INFP
Middle: ESTP
Youngest: INTJ

Bonus: Dad is an oldest child INTP

Personally, I think MBTI type is based on the cognitive functions you receive at birth, and although birth order may affect how your type is manifested, it does not affect your type. Just my opinion based on research and experience.

Laura T Dishong (not verified) says...

My daughter and I are both only children and we're both ENFPs. My husband is also an only child but he's an ISFJ. I suspect that only children may be much harder to pin down than people realize.

karilisa (not verified) says...

Seems to be true in my family. I am the oldest of three daughters. I am INFJ, next sister is ENFP and third is ESFP. Father is ENFJ and mother is ESFJ.

Guest (not verified) says...

Haha that's funny! I'm the eldest; an INFP, but I associate more closely with the middle child. I've always been the mediator in the family, and I have a huge distrust of authority. My youngest sibling matches his description pretty well, and my parents actually match the eldest description almost to a 'T'.

Guest (not verified) says...

the oldest sister is ENF, a rule breaker, independent. Didnt finish schooling.My brother and I were the infj's/intj's I think. Both went on to continued learning and qualifications. Doesn't fit with theory. Check out the "Dunedin" study. Largest ongoing study in the world.

GemzL99 says...

First born and ENFP.

Alpha (not verified) says...

I'm the last born and im a ENFP.

Guest (not verified) says...

My step-brother (eldest) acts more like the youngest and I (youngest) acts more like the first born. I suspect him of being and ExFP and I am an INFJ.

ASP (not verified) says...

I am a first born and a INFP.

Guest (not verified) says...

I am an ENTP, which is actually pretty much opposite to the middle child "Peacekeeping, non-confrontational, non-competitive, diplomatic and compromising." ENTP's are known to enjoy debates, arguments and playing the devil's advocate, and so I find it difficult to believe that my birth order truly plays a huge part in my personality, because I am not anything like the middle child described.

Guest (not verified) says...

I am also an ENTP middle child, and I don't fit the criteria at all. My older sister is an ISFP, but she is very unorganized, and not much a leader,, but my little sister whose type I don't know perfectly fits the description of the youngest child. I think that this means that maybe more so than birth order, is the personalities of not just the parents, but maybe the siblings before, because who wants to be or is inclined to be the same as a person they are constantly interacting with. The dynamic would t function properly, but due to common tendencies of first born children , later siblings could potentially fall into the type of pattern found in this study.

A. Ringlien (not verified) says...

I'm the oldest and I have a little brother. He is such a suck-up to my parents and I'm perceived as the independent and seclusive one. This is really accurate.

Guest (not verified) says...

Oldest - INFJ

Guest (not verified) says...

That's not fully true, while i'm the second child, i'm the shy and seclusive one of all three brothers. and my older brother is the outgoing one.

Guest (not verified) says...

I have six children with 11 years between the oldest and the youngest. They start off fairly outgoing with good social skills and this diminishes further down the line, becoming more introverted and socially awkward. I put this down to the fact that the oldest had to go out and meet people, whereas the youngest are always in a crowd, whether at home, or out and about. They have the security and comfort of all their siblings around them, appearing to be confident and extrovert - but when you take them out of that crowd, they find it difficult to really engage with other groups of people except with very close friends. I do believe they have introversion in their initial make-up. My husband and I are both introverts, (I am an introvert that always thought I was an extrovert) so we always prefer life at home with the kids, so that attitude hasn't helped them. The first born is naturally outgoing, a risk taker and party animal - but slapped on top of that is reliability and responsibility which I don't think he'd have if he were born further down the line. I do think he has learnt that from being the first born. So in conclusion, I think there is an initial personality type which is enhanced and/or added to according to the birth place and finally further enhanced or challenged by the family personality types and the environment they live and interact in. It is always going to be a very complex situation, which is why a very expert MBTI 'interpreter' should help guide a person when they are establishing their own personality type, rather than just do an online test - no matter how comprehensive it may be.

INFJ1961 says...

I'm the youngest of four, with 8 years between me and the next sibling. I'm the only son. I'm an INFJ. My youngest sister, the one who was the baby for 8 years before I came along, is a tried and true extravert, and other than agreeable, matches the description of last born. The rest of us are introverts, parents included (although I thought my mother was for sure an extravert until I gave her a test to take).

Aerith (not verified) says...

My older sister (we are a year and a half apart) doesn’t seem to apply with the first-born stereotype. She’s an ENFP. I’m the youngest (there are only two children in my family) I’m the middle and youngest child but I don’t know if I fit into the stereotypes...maybe just a little bit, I’m an ISFJ.

Guest (not verified) says...

I don't think this is completely correct. I think this based on the responsibilities put on a child over time. For example, I am the middle child. I am introverted and I have as much responsibilities and expectations as my brother who is a year older than me. In fact in some cases my brother has greater liberties and can be a little bit more carefree than I can based on my culture since I am the oldest girl I have a greater expectation to do more work and be obedient. As of my sister she fits more with the third child stereotype. She is more extroverted then me with and more carefree. She is the youngest and often gets to relax more then my brother and I do. Also when it comes to comparing personality types I am pretty sure, even as the eldest I am more of a eldest sibling stereotype than my brother does in some ways. I am introverted and he is more extroverted than I am and I am often as goal oriented as he is if not more so.

Guest (not verified) says...

I am an INTJ, the younger (by three minutes) twin. My sister is ENTJ. I would say my younger brother is ESFJ.

Guest (not verified) says...

I'm the oldest and I'm ESTP. My sister is INTP.

Eric Dyer (not verified) says...

I’m really impressed with your article, such great & usefull knowledge you mentioned here 

Laurie Cartrette (not verified) says...

I'm an INTJ, only child. So more like a first born of the 3. 

An ENFJ female (not verified) says...

First born ENFJ

Share your thoughts


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