# What causes personality types?



## BearRight (Mar 6, 2010)

What causes the different personality types?
Why are there 16 different personality types?

It has to have something to do how our brains are wired.
But personality type isn't hereditary.
Is it caused by genes still?
Is it the structure of the brain?
Or is it hormones?
Neurotransmitters?
As if there were 16 different cocktails?

I would think neurotransmitters could cause the different personality types, but the amounts and types of neurotransmitters would be dictated by genes mostly. I believe Te dominants have high testosterone and adrenaline levels, but there's no evidence about this. There are female ESTJs and ENTJs too, so testosterone cannot be the answer.


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## Hosker (Jan 19, 2011)

You're basically getting into nature vs nurture. Nobody really knows; it's probably a mix of the two.


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## alionsroar (Jun 5, 2010)

I don't think there are 16 different personality types. Just 16 types in the myer-briggs system.
To complicate things we could introduce more variables, for example, divide each of the 16 types into 2 or 3 to make 32 or more types. Or combine myer-briggs with socionics with enneagram. So potentially, you could have 16x16x9types. So you have a person who's an ESTP, SEE, E8 who is different from some other ESTPs.

As to what exactly causes someone to grow up preferring, extraverted or introverted thinking, sensing, intuiting or feeling. I don't know.


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## BearRight (Mar 6, 2010)

It must be nature. I can detect that a one five year old girl is an ESFP - that's certain and she's been lively and smiley since she was born. This could be tested in daycares and elementary schools. I believe personality types can be detected in kids, although the functions gain strength during life (the dominant function would be detected still). I remember from my childhood how there were girls spending time in groups and when I think about that now they had to be xSFJs. In my opinion nurture just adds some edges, but it cannot change the underlying Myers-Briggs personality type.

If the personality types aren't caused by genes, the mother's womb and hormones during development would be the prime suspect. What the genes or the womb would affect is the wiring of the childs brain be that levels and kinds of neurotransmitters or real differences in the ways the nervous system works. Nothing happens by accident, there's always a reason.

Insight: Personality types are definately caused by genes, and personality type classifications are just like blood group classifications. It's kind of similar system, but we haven't yet found out everything there is.


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## streetlightfancy (Aug 14, 2010)

I don't really know for sure, but if I had to guess it would be the structure of our brains - which is affected by a lot of different factors including both prenatal and postnatal environments.

Does anyone know of identical twins who are different types?


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## ardentauthor (Jul 7, 2011)

streetlightfancy said:


> I don't really know for sure, but if I had to guess it would be the structure of our brains - which is affected by a lot of different factors including both prenatal and postnatal environments.
> 
> Does anyone know of identical twins who are different types?


I knew some twins a few years ago. I'm afraid I don't know their actually type, but I'm positive that one was introverted and the other was extraverted. I didn't know them very well, so I can't take a guess at the remaining.

...I agree with you; I think it's a mixture of both nature and nurture that determines personality.


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## cyamitide (Jul 8, 2010)

BearRight said:


> It must be nature. I can detect that a one five year old girl is an ESFP - that's certain and she's been lively and smiley since she was born. ...


There have been 6 years of nurture/environmental influence for that girl before you could detect she is ESFP. From the point that her mother's egg and her father's sperm combined together it's all environmental influences, including 9 months she spent in the womb of her mother being subjected to her mother's biochemistry, plus several years she spent as a baby. So if you can detect personality preferences in kids that young of age that does not mean that it's all genetic.

Nurture/environment can have paramount influence as twin studies demonstrate. There are identical twins who don't share same interests, talents, and even sex gender preference.


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## tachyon (Jan 7, 2017)

I think that the reason for the existence of MBTI Personality Types is actually rooted in Adlerian psychology. The 16 personality types are just the most common manifestations of Adlerian psychology. Simply put the 16 personality types are 16 different "survival strategies" that we develop as infants to make the most efficient of an individual's available resources (mental, physical,whatnot). 

Genetics obviously plays a part to this (I'm thinking it would be the N/S dominance that would be most affected by genetics after that I/E but less so T/F and J/P).


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## Eset (Jun 7, 2016)

> What causes the different personality types?


There is no particular cause other than; people are different.



> Why are there 16 different personality types?


Because the system said so.



> But personality type isn't hereditary.


That is what it implies.



> Is it caused by genes still?


That is what it implies.



> Is it the structure of the brain?


That is what it implies.



> Or is it hormones?


It does not imply such.



> Neurotransmitters?


It does not imply such.

There is no empirical way to study MBTI and it's cause and affect, so there is little reason to ask such questions since your answers will not be fulfilled.


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## MusiCago (Jan 3, 2017)

I've thought about this a lot and the other day I had an Ni realization that both of my parents are ENFP (dad) and ENFJ (mom). Therefor it must be why I've always struggled to differentiate if I was either INFP or INFJ. I remember in elementary school I was very extroverted, very loud spoken and loved attention.. Well in second grade I was sent to live with my grandma (not anything i did wrong but my parents made some mistakes and wanted me to be safe) so I have lived with her ever since (I'm 16). Therefore it would make sense where my Introversion came from because I made my grandma take the test and she is an introvert herself, being an ISFJ. I was brought up to be quiet and reserved (seemed like a manners thing when I was younger.) So in terms of nature vs nurture, I believe it comes from both.


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