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By the end of this section, you will be able to:
  • Discuss the findings of the Minnesota Study of Twins Reared Apart as they relate to personality and genetics
  • Discuss temperament and describe the three infant temperaments identified by Thomas and Chess
  • Discuss the evolutionary perspective on personality development

How much of our personality is in-born and biological, and how much is influenced by the environment and culture we are raised in? Psychologists who favor the biological approach believe that inherited predispositions as well as physiological processes can be used to explain differences in our personalities (Burger, 2008).

In the field of behavioral genetics, the Minnesota Study of Twins Reared Apart —a well-known study of the genetic basis for personality—conducted research with twins from 1979 to 1999. In studying 350 pairs of twins, including pairs of identical and fraternal twins reared together and apart, researchers found that identical twins, whether raised together or apart, have very similar personalities (Bouchard, 1994; Bouchard, Lykken, McGue, Segal,&Tellegen, 1990; Segal, 2012). These findings suggest the heritability of some personality traits. Heritability refers to the proportion of difference among people that is attributed to genetics. Some of the traits that the study reported as having more than a 0.50 heritability ratio include leadership, obedience to authority, a sense of well-being, alienation, resistance to stress, and fearfulness. The implication is that some aspects of our personalities are largely controlled by genetics; however, it’s important to point out that traits are not determined by a single gene, but by a combination of many genes, as well as by epigenetic factors that control whether the genes are expressed.

Temperament

Most contemporary psychologists believe temperament has a biological basis due to its appearance very early in our lives (Rothbart, 2011). As you learned when you studied lifespan development, Thomas and Chess (1977) found that babies could be categorized into one of three temperaments: easy, difficult, or slow to warm up. However, environmental factors (family interactions, for example) and maturation can affect the ways in which children’s personalities are expressed (Carter et al., 2008).

Research suggests that there are two dimensions of our temperament that are important parts of our adult personality—reactivity and self-regulation (Rothbart, Ahadi,&Evans, 2000). Reactivity refers to how we respond to new or challenging environmental stimuli; self-regulation refers to our ability to control that response (Rothbart&Derryberry, 1981; Rothbart, Sheese, Rueda,&Posner, 2011). For example, one person may immediately respond to new stimuli with a high level of anxiety, while another barely notices it.

Body type and temperament

Is there an association between your body type and your temperament? The constitutional perspective, which examines the relationship between the structure of the human body and behavior, seeks to answer this question (Genovese, 2008). The first comprehensive system of constitutional psychology was proposed by American psychologist William H. Sheldon (1940, 1942). He believed that your body type can be linked to your personality. Sheldon’s life’s work was spent observing human bodies and temperaments. Based on his observations and interviews of hundreds of people, he proposed three body/personality types, which he called somatotypes.

The three somatotypes are ectomorphs, endomorphs, and mesomorphs ( [link] ). Ectomorphs are thin with a small bone structure and very little fat on their bodies. According to Sheldon, the ectomorph personality is anxious, self-conscious, artistic, thoughtful, quiet, and private. They enjoy intellectual stimulation and feel uncomfortable in social situations. Actors Adrien Brody and Nicole Kidman would be characterized as ectomorphs. Endomorphs are the opposite of ectomorphs. Endomorphs have narrow shoulders and wide hips, and carry extra fat on their round bodies. Sheldon described endomorphs as being relaxed, comfortable, good-humored, even-tempered, sociable, and tolerant. Endomorphs enjoy affection and detest disapproval. Queen Latifah and Jack Black would be considered endomorphs. The third somatotype is the mesomorph. This body type falls between the ectomorph and the endomorph. Mesomorphs have large bone structure, well-defined muscles, broad shoulders, narrow waists, and attractive, strong bodies. According to Sheldon, mesomorphs are adventurous, assertive, competitive, and fearless. They are curious and enjoy trying new things, but can also be obnoxious and aggressive. Channing Tatum and Scarlett Johannson would likely be mesomorphs.

The outlines of three human somatotypes are shown. The first is labeled, “Endomorph,” the second is labeled “Mesomorph,” and the third is labeled “Ectomorph.” Endomorphs are slightly larger than mesomorphs, and ectomorphs are slightly smaller than mesomorphs.
Sheldon proposed three somatotypes: endomorphs, mesomorphs, and ectomorphs. Do you think Sheldon’s ideas about somatotypes are generally accurate about most people?

Sheldon (1949) also conducted further research into somatotypes and criminality. He measured the physical proportions of hundreds of juvenile delinquent boys in comparison to male college students, and found that problem youth were primarily mesomorphs. Why might this be? Perhaps it’s because they are quick to anger and don’t have the restraint demonstrated by ectomorphs. Maybe it’s because a person with a mesomorphic body type reflects high levels of testosterone, which may lead to more aggressive behavior. Can you think of other explanations for Sheldon’s findings?

Sheldon’s method of somatotyping is not without criticism, as it has been considered largely subjective (Carter&Heath, 1990; Cortés&Gatti, 1972; Parnell, 1958). More systematic and controlled research methods did not support his findings (Eysenck, 1970). Consequently, it’s not uncommon to see his theory labeled as pseudoscience, much like Gall’s theory of phrenology (Rafter, 2007; Rosenbaum, 1995). However, studies involving correlations between somatotype, temperament, and children’s school performance (Sanford et al., 1943; Parnell); somatotype and performance of pilots during wartime (Damon, 1955); and somatotype and temperament (Peterson, Liivamagi,&Koskel, 2006) did support his theory.

Summary

Some aspects of our personalities are largely controlled by genetics; however, environmental factors (such as family interactions) and maturation can affect the ways in which children’s personalities are expressed.

Personal application questions

Research suggests that many of our personality characteristics have a genetic component. What traits do you think you inherited from your parents? Provide examples. How might modeling (environment) influenced your characteristics as well?

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Questions & Answers

how do you analyze body language
Kailyn Reply
School of thoughts by the scholars
bright Reply
what subject matter of psy
muhammad Reply
Genetics
Awet
do you think that Candace benefited or suffered as a result of consistently being passed on to the next grade?
Cincona Reply
what is Fixed interval
Paradise Reply
Which of the following is not true about physical punishment of children
Chris Reply
who is the writer of this book
Shiv Reply
I think people will not be skeptical but will be interested to know about it
Kabir Reply
Does anyone else here think that God is a made-up concept, developed by different cultures as a coping mechanism with the reality of nothingness and for reproduction? (just my thoughts)
Raman
idk if its a made up concept..or there's actually a super entity in the outer space controlling every thing..but I think it's the concept of God is a necessity for the being of righteous communities. The desire for heaven and the fear of hell is the only thing that keeps many people on the good path
Junaid
(Just my thoughts)
Junaid
Do anyone think that the only way to improve a country 😂 is by having a good education so that people can stand by their selves, and hopefully will help the country.
Genlaiza
Yes . But they aslo need a good economical foundation.
sayantan
I think the concept of God it is not made-up concept but it is made by the feelings of the people because God is nature and from the fact that we feel nature since i is the one who provides for all of us so as a sign of gratitude for everything that we are having from this world we made it as a God
Genlaiza
sure
Prince
That's something Genlaiza....reminds me a quote of Ramana Maharshi .."What is God? The question itself contains the answer: What is,(is) God."
Junaid
thank you very much by the way I am still in high school I'm just having an advance reading
Genlaiza
Good for you :)
Junaid
Any suggestions?
Junaid
if u know what is God or who is ..I think vedanta , one of the oldest treatise related to God . According to yajur veda -God Supreme or Supreme Spirit has no ‘Pratima’ (idol) or material shape. He cannot be seen directly by anyone. He pervades all beings and all directions. Thus,   Idolatry doe
sayantan
I think god is cannot be known because my father said god is nature so can a nature be known or studied? god is not something that should know but it is be feelled and believed and I don't think god is about superiority
Genlaiza
I am just saying..
Genlaiza
yup ..you aslo define God as a creator of our universe because when you goes deep though nature or universe you see that everything is organize with a precise mathematical design.. so you aslo say that if u understand the rhythm of our universe or nature then perhaps you understand what God says .
sayantan
In my thought god is a mind of our soul.bcoz when we see everything that what a manner we can understand, how to treat or how to realize,how to respect and so on...you know the only work of God is to realize who we are ,and what was the problem or anything behind us ..if it is the loss or soul pain
rajy
what causes the brain to produce melatonin
Kali Reply
melatonin is secreted by the pineal gland in the brain. it is a hormone that helps your body prepare for sleep and is activated at night when the CNS 'turns on' the pineal to actively produce melatonin. it remain mostly 'inactive' in the day time.
paschal
why do people sleep in the day time
John
melatonin acts as a 'time cue' anticipating sleep. And since it influences our sleep-wake cycle and circadian rhythm (or body-clock), it comes to play when you didnt get enough sleep time or when you are fatigued. Hence, it activation during the day. Remember, the CNS is the 'commander' of your body
paschal
sleeping in the day time, can it be a habit?
John
anything u do very often will eventually become a habit. but u must understand that peoples' biosystem can be different - what can be a habit in mr A might be a hormonal imbalance in mr B. so, if u suddenly find yourself sleeping often in the daytime (when u are not working nightshifts) see a doctor
paschal
I want to study psychology but I don't know how to start it.
John
yes
Prince
Naturally, John, we all use psychology in our daily interactions. if you want to study it professionally, then you have to attend an educational institution or take an online course. you can do it.
paschal
yes I can do it
Prince
There are many resources on the internet that can aid you in your endeavour.
paschal
whats the topic? be i just downloaded this app and trying to figure it out.
Roxanna Reply
is this your begining in psychology ?
KhaLid
This is my beginning in psychology
Junaid
I am new to psychology
Dom
what are u pursuing ba psychology or applied psychology
Sajan
I am new here any friend please?
Teben Reply
I'm new too, hello friend
Mark
i am also new here
Maliha
i'm new three😂
Mohammad
i'm new three😂
Mohammad
Me too....How you all doing?
Junaid
I good thank you, just in a government lockdown, and now with no job bit searching for a new one in something on the global digital platform would be nice a start to a new job career, from turning a hobby into a new career.
Mark
I am retrospectively new here 😂😂😂😂 Hey everyone !
KhaLid
hi
sayali
Hi Im new for this chat!
Shyam
Let me introduce myself
Shyam
That's great *MARK* I'm also bit searching for a job on digital marketing
Shyam
yes
Bikram
if anyone needs any concepts about psychology lemme know !
KhaLid
I am new new here too
Dom
certainly Salma .....
KhaLid
go ahead ... how can I help you?
KhaLid
Hi
Aliena
hi
Justina
Hello everyone. How u guys hanging?
paschal
I have been struggling
Bosie
What have u been struggling with?
paschal
finding a way to get a laptop to do my work on.
Bosie
Where are you from?
paschal
hi..i need help with my assignment..i need 3 written role plays and each role play i need to use 2 different counseling therapies.
Ashital Reply
why they didn't investigate another person?
NFAK Reply
?
Leuka
?
Cary
be aware your life and others life's It is humanity
muhammad
what is the topic?
paschal
why do people say that girls are more emotional than boys
Soohie Reply
***goodtherapy.org/blog/do-boys-and-girls-express-emotions-differently-1226122?fbclid=IwAR1qdt09vHmDoMHzkoFP8MBRr8nocv9P_I3zluC4rpQ7yo0wO7wVyFwQiB4
Sarah
thanks
NishaOfficial
no problem
Sarah
Wilhem Wundt's introspection technique with his own strict rules for the experiment. Is the technique able to recognize symptoms of mental illnesses, like schizophrenia or dementia for example, or is it only applicable to a certain degree? If so, what is the extent of this technique he used?
Shilla Reply
Yes
Mehmood
Oh, so, yes it can recognize mental illness symptoms?
Shilla
Pls I want to study psychology in higher education but am a bit confused between educational psychology and social psychology which is better?
Odey
confused about what these are two particular fields of psychology tell me odey in which you are interested ?
KhaLid
***differencebetween.com/difference-between-psychology-and-vs-social-psychology/
Sarah
psychology deals with mental processes and behavior in an individual while social psychology deals with society and their influence on an individual
Sarah
what about cognitive psychology and cognitive neuroscience?
Mehmood
Am interested studying social psychology bt I dnt knw the one that is better
Odey
I can't see the full message u want to know about cognitive psychology and cognitive what was the last part
Sarah
cognitive psychology and cognitive neuroscience
Mehmood
Cognitive psychology is more focused on information processing and behavior. Cognitive neuroscience studies the underlying biology of information processing and behavior.
Sarah
Cognitive neuroscience overlaps with cognitive psychology, and focuses on the neural substrates of mental processes and their behavioral manifestations.
Sarah
According to the American Psychological Association (APA), cognitive psychology is the “study of higher mental processes such as attention, language use, memory, perception, problem solving, and thinking.” As a scientific study of mind and mental functioning, the core focus of modern cognitive psych
Sarah
***bestpsychologydegrees.com/faq/what-is-cognitive-psychology/
Sarah
I'm currently in college studying for my BA in Science of Psychology which is General Psychology
Sarah
thanks Sarah. can a psychologist be a cognitive neuroscientist? or this domain is out of reach from psychologist s
Mehmood
Odey have u looked into the different types of social psychology and what each of them are?
Sarah
cognitive neuroscientists all study psychology biology neurologist chemistry and philosophy. they typically have training in at least one of these disciplines and can work in a variety of roles, from conducting brain research to helping therapy clients overcome mental illness.
Sarah
so I would say yes a psychologist can be a neuroscientist after furthering their education more
Sarah
Pls Sarah, if u can help me wit any material on the difference I will rili appreciate, we find it difficult to get good psychology material in my country
Odey
yes Sarah. it seems it is an interdisciplinary field of study. I don't know whether most of th universities will provide education in cognitive neuroscience. it seems so expensive and laborious to me. what do you think
Mehmood
yes Sarah. it seems it is an interdisciplinary field of study. I don't know whether most of th universities will provide education in cognitive neuroscience. it seems so expensive and laborious to me. what do you think
Mehmood
***careersinpsychology.org/becoming-a-cognitive-neuroscientist
Sarah
Odey here is a link on social psychology and their different types for you to explore ***bestselling.com/research-areas-in-social-psychology-2795913
Sarah
nobody wants to help answer and explain the question I had? Besides a simple yes? And you guys went on with a different discussion here -_- Thank you very much
Shilla
reask your question again and I'm sorry
Sarah
Wilhem Wundt's introspection technique with his own strict rules for the experiment. Is the technique able to recognize symptoms of mental illnesses, like schizophrenia or dementia for example, or is it only applicable to a certain degree? If so, what is the extent of this technique he used?
Shilla
It's okay, forgiven 😂
Shilla
I have to look in my text for that I havent gotten there yet
Sarah
thank you
Sarah
I'm still looking i hope someone else can help. Forgive me?
Sarah
hey guys can anybody provide me.notes regarding indian psychology and how it changes according to time
nitesh
you mean history of indian psychology?
PUSHPITA
yes would be interesting... as individual psychology is influenced by socialization too... my opinion regards
Neelkanth

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Source:  OpenStax, Psychology. OpenStax CNX. Feb 03, 2015 Download for free at https://legacy.cnx.org/content/col11629/1.5
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