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Biological theory

The Biological Theory of personality suggests that key personality components are inherited, influenced by our genes. Twin studies show similarities in traits like social potency and traditionalism, even when raised apart. However, genes don't solely determine personality; environmental factors also play a role. Created by Shreena Desai.

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  • blobby green style avatar for user DRO93
    I enjoy studying every part of the MCAT except this section. Seems like ridiculously pointless information
    (42 votes)
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  • purple pi purple style avatar for user Sexy A.I.
    why are these considered theories and not hypotheses? psychology like philosophy is a soft science so why are these subjective opinions elevated to theories?
    (14 votes)
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    • piceratops seedling style avatar for user Anne Mclean
      Presumably it's a terminology difference - using "theory" in the common sense of the word to mean a systematic, and well fleshed out explanation, without the implication of mountains of scientific evidence that the word carries in the hard sciences. Honestly I'm not sure the kind of evidence required for a "theory" in hard sciences is even a realistic concept when you're discussing something as amorphous as "personality."
      (7 votes)
  • leaf green style avatar for user 福龍丸
    Shouldn't the title also be "biologic theory", not "biological theory"?
    (12 votes)
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  • leaf green style avatar for user dsc6876
    Is the mitochondria the powerhouse of the cell?
    (5 votes)
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  • leafers seedling style avatar for user Michelle
    I don't understand the beginning comparison between the Brain (traits) and Behavior (genetics/evolution). She made it sound like there was a contrast between these two origins of personality, but this was not expounded upon and I'm still a little unsure of the distinction.
    (3 votes)
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  • blobby green style avatar for user Haj
    On multiple occasions, it was said if you have this gene. I just wanted to make this sentence more accurate by saying: if you have the allele of this gene.

    We almost (except those with deletions, and monosomy...) have the same genes. However, we have different alleles of these genes.
    (2 votes)
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  • orange juice squid orange style avatar for user Kevin Ohlsson
    What's the name of the tests that conducted the result of social potency and traditionalism in twins raised apart? Thanks.
    (2 votes)
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  • primosaur ultimate style avatar for user Ruby Rose
    Wait, isn't it obvious that identical twins' personalities would be different? They have a mother and a father, and only because they are identical in appearance means the genes are different. They have some similarities and differences because they have different parents. The only way identical twins would be identical is if they were cloned from one parent only, correct? If this is true, then the Biologic Theory is true, then it's actually proven.
    (0 votes)
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    • leaf yellow style avatar for user Rick Roxas
      Identical twins are formed and split from the same fertilized egg. This means that they have the same genetic make-up. But other factors, including biological ones like DNA methylation, and sociological ones like upbringing, influence their personalities.
      What makes them interesting as subjects of personality experiments is that the similarity of their genetic make-up makes the "nature" variable controlled to some degree, and it lets scientists focus on the effects of different environments on the personality of a person.
      Of course, making multiple human clones and putting them into different environments so you can study the differences in their personality offers greater experimentation opportunities, but that would be in conflict with human ethics. :)
      (8 votes)
  • marcimus pink style avatar for user Aisha ahmed
    does that mean different approaches are used for different people? can a person uses all theories to establish a personality?
    (1 vote)
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    • duskpin ultimate style avatar for user Cait_Alayne
      The reason there are so many theories of personality is that none of them can be called a "law". That is, we are unsure which one, if any, is the "correct" theory. Personalities are complicated and it is unlikely that only one theory actually explains every facet of a personality. That means several different approaches could be used to explain an individual's behavior.
      (1 vote)
  • piceratops ultimate style avatar for user Mustafa Shahbaz
    Even if you've reached an older age like lets say 20-30 years old, can you still change or "grow" your behaviours (like the types that they study with these twins at a young age) even when older? So a person who was raised in a bad environment when raised in a more calming and caring environment when theyre much older, can they change their behaviour for good?
    (1 vote)
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    • duskpin ultimate style avatar for user Mary
      It can be very difficult, if not impossible to change core behaviors.

      When I experience a situation that causes high anxiety within me I can start to feel my life is being threatened. As a youngster mean things were done to me while the person doing the mean things was screaming I could/should/can/will kill you. My death would never take place at that moment but I would walk on egg shells for days. Now, if I speak out of turn, or contradict my boss I can go home and be absolutely terrified that I will be losing my job in the next 48 hours.

      It is the same feeling of fear from when I was a child believing that sometime in the next day or two I could say the wrong thing, look the wrong way or sneeze at the wrong time and I could likely die but not having any idea what would actually trigger my death was a big part of the fear. As an adult and as a child when feeling that intense fear I can/could only cry and try to hide. Once I cross that threshold it takes me a week or two to start to feel safe again.

      I believe my challenges are biologic and events in my life triggered certain genes to express themselves certain ways. If I grew up in a loving and functional environment my environment would have triggered different genes or maybe the same genes but the expression of behavior is different.

      Growing up with repeated existential threats causes different behaviors than growing up with repeated kindnesses.
      (1 vote)

Video transcript

All right. Let's talk about yet another theory of personality called the biologic theory. But let me first start off by saying that there are many variations to this theory. Some relate more specifically to the brain. And others, like the evolutionary approach, the evolutionary psychology approach, is more concerned with behavior rather than traits. So for example, the evolutionary psychology theorizes that males and females have different mating strategies that influence the costs associated with passing on genetic material. For example, men have lots of sexual partners, but women are more selective due to the costs of pregnancy. Now, this case I just said is probably the most dominant psychological and biological theory to date. And Buss is one of the major psychologists associated with that. Now, taking all of this aside, the biologic theory suggests that important components of personality are inherited. So that's the key word. Important components are inherited or determined in part by our genes. And I'm not talking about those things we wear. But I'm talking about the things that are buried deep within our cell's nucleus. And to study biologic and genetic effects on personality, researchers always turn to look at twins, because twins studies are used in many psychological theories to tease out environmental versus genetic characteristics. Now, more specifically, they look at identical twins. And that's because they have the same genetic makeup. So that will eliminate one factor of variation. So they look at identical twins who were raised apart from each other or in different environments. Now, results showed that even though the twins were reared separately at an early age, they still had similar personalities. Certain traits that we give credit to the trait theory for categorizing were more influenced by heredity than others were. And one example is the social potency trait. And social potency is the degree to which a person assumes leadership and mastery roles in a social situation. So this was found to be common in both twins that were raised separately. And another trait, called traditionalism, which is the tendency to follow authority, was also shown to be common with both twins. But at the same time, there were other traits that had weaker genetic components. And some examples of this is the trait of achievement. It was stronger in one twin versus another. And same with closeness. So some researchers have even gone further to look at specific genes to try and relate to our personality. One example is that people with a longer dopamine-4 receptor gene are more likely to be thrill seekers. So basically, if you have this gene, you may love roller coasters and probably want to skydive one day. Hey, that sounds a lot like me. No. But don't think that just because you have a gene, you're destined to have that personality. We all know that. So just because you have a longer dopamine-4 receptor gene doesn't mean you will be a thrill seeker for sure. There are a lot of other things, such as environmental factors, that are coupled with genes that account for variation. Like looking back at this case of the identical twins. Obviously, there are parts of their personality that we can attribute to how they were reared and differences in their environment growing up. Now, another key word to know with this theory and many other theories is the word "temperament." Now, temperament is an innate disposition. And that's why I bring it up with the biologic theory, because of that word, "innate." Innate usually means brought up by genetics, or it's inherited. So temperament is anything from our mood to our activity level. And it's usually consistent throughout our life. And temperament is not solely just associated with the biologic theory. It's also associated with several other theories, including the trait theory. So biologic principles can underlie important concepts in many personality theories. So overall, the important takeaway of this tutorial is that our inherited genes, to some degree, lead to our traits, which then in turn lead to our behavior or our personality. But this isn't an end-all, be-all relationship. Our genes don't always determine our total personality. There has to be other things that account for this. And that includes environmental factors.