Select your language

Suggested languages for you:
Log In Start studying!
StudySmarter - The all-in-one study app.
4.8 • +11k Ratings
More than 3 Million Downloads
Free
|
|

All-in-one learning app

  • Flashcards
  • NotesNotes
  • ExplanationsExplanations
  • Study Planner
  • Textbook solutions
Start studying

Heritability

Save Save
Print Print
Edit Edit
Sign up to use all features for free. Sign up now
Heritability

What makes you, you?

Why are your eyes brown, but your friend's eyes blue? Why are you more prone to anxiety, while your friend is always calm and collected? Scientists quantify how much genetics affect these differences by determining heritability.

  • What is heritability?
  • How is heritability influential in psychology?
  • What is the heritability coefficient?
  • Why are twin studies important in showing heritability?

Heritability Definition in Psychology

As you know, the observable characteristics that we possess are called phenotypes. Both our genes and environment interact to determine these characteristics. Genotype refers to the genetic makeup of a person. Within a population, the variations in phenotype can be vast. So how do you measure these differences?

You use heritability.

Heritability is the statistical measurement of how genes influence the individual variations observed within a population.

Here are some examples of phenotypes that often have a high heritability:

  • Eye color
  • Skin color
  • Height
  • Dominant hand
  • Dimples

Heritability hair texture and heritability example psychology StudySmarter
Hair texture often has high heritability, freepik.com

What Does Heritability Not Tell Us?

Now that we know what heritability is, let's briefly discuss what heritability is not. Heritability doesn't measure how much of a person's phenotype is influenced by genes and the environment. Heritability only measures the effect of genes on the variations that we observe.

Say your IQ is 100, and your friend's IQ is 110. Heritability does not measure how much your genes influence your IQ, but rather how many genes influence the difference between your IQ, and that of your friend.

Furthermore, heritability does not specify what genes affect the phenotypic variations. Heritability, for example, does not determine that there is just one gene that affects the difference in IQ in the previous example. Instead, many genotypes are at play in the heritability coefficient.

Twin and Adoption Studies in Heritability

One of the most effective approaches to exploring heritability is twin and adoption studies. When looking at a person's genetic makeup, we know that each parent passes down 50 percent of their genes to their offspring. Therefore, siblings share 50 percent of their genes with each other. However, identical twins receive the same genes from their parents, meaning they share 100 percent of their genetic makeup.

RelationshipRelationship Coefficient (%)
Identical twins100
Fraternal twins50
Full siblings50
Half siblings25
Aunt/Uncle25
First cousins12.5

Twin Studies

While identical twins share 100 percent of their genetic makeup, the number of copies of those genes might differ. Also, some placental abnormalities during prenatal development can impact how much nutrients each twin receives, potentially affecting phenotypic presentation. However, identical twin studies allow researchers to "control" heredity. This is has led to many discoveries regarding heritability vs environmental impact.

Heritability twins and heritability psychology example StudySmarterIdentical twins share 100 percent of their genetic makeup, freepik.com

Adoption Studies

Adoption studies offer another ideal situation for researchers to study the impact of genes and environment on characteristic differences. Suppose identical twins were adopted by different families and raised in different environments. In that case, researchers can use these circumstances to identify similarities that remained regardless of the environment, and what differences were created due to the environment. Researchers also might observe correlations between adopted children and their biological parents to understand the heritability of certain traits that might have been passed down.

Heritability Coefficient in Psychology

Heritability is expressed as a proportion, which we often refer to as the heritability coefficient.

Heritability coefficient is a proportion used to quantify the variation of a trait or characteristic that is due to a genotype.

As a proportion, the numerical value of the heritability coefficient ranges between 0.0 and 1.0. A heritability coefficient of 0.0 means that genes do not affect the individual phenotypic differences. On the other hand, a heritability coefficient of 1.0 means that the individual variations are solely due to genetic makeup.

You can calculate heritability using the following formula, where Vg is the variation in genotype and Vp is the variation in phenotype: H2 = Vg / Vp

Examples of Heritability in Psychology

Heritability in psychology explores a broad range of character traits and behaviors. Let's look specifically at the heritability of intelligence and personality.

Heritability of Personality

Behavior genetics studies also seek to understand the heritability of personality. Personality is widely broken down into five main traits:

  • Extraversion-Introversion (outgoing/reserved; processing the world around us internally or externally)
  • Neuroticism (emotional stability)
  • Conscientiousness (dependability/responsibility/motivation)
  • Agreeableness (cooperation/helpfulness)
  • Openness to experience (imagination/artistic sensitivity/curiosity)

Twin studies come into play once again. Many studies have used identical twins to determine the heritability of personality. For example, Johnson (2016) found that personality traits are 40-60 percent heritable.

Heritability of Intelligence

If intelligence were a 100 percent heritable trait, people with the same genotype would have identical test scores. Twin studies are extremely valuable in this case because they recreate an otherwise hypothetical situation. Many studies have explored the correlation between adopted children and their biological parents to identify the heritability of intelligence. For example, a study done by Petrill (2003) found evidence to support that 50-70 percent of the IQ variation within a group is due to genes.

Other studies have observed the correlation of IQ scores between identical twins who grew up together and those who did not, versus full-siblings who grew up together and those who did not. If environment played a more significant role in intelligence than genes, there would be very little difference in the correlation of IQ scores of twins and siblings who grew up together. However, Bouchard & McGue (1981) found a noticeable drop, more evidence to support the claim that intelligence can be a highly heritable trait.

What Is Low Heritability?

If genes do not heavily determine the variation of a trait, it has low heritability. In this case, environmental factors greatly impact the trait's variability. The proportion of environmental factors that affect the variability of a trait can be determined by subtracting the heritability coefficient from 1.0. If a personality trait's heritability is 40 percent, or .40, then the environmental factors have a 60 percent or .60 effect on the variation of that trait.

Traits such as walking and breathing have low heritability, because these are usually universal traits with slight variations. And many times, the variation is due to environmental factors, such as a car accident, rather than genetic factors. Heritability can also be a fluid measurement. It can increase or decrease based on the population that is being observed. Heredity becomes the primary explanation for differences as the environments become more similar. Contrarily, as heredity becomes more similar, the environment becomes the primary explanation for differences.

How Is Heritability Useful in Psychological Research?

Heritability is an essential measurement in psychology disciplines such as molecular behavior genetics.

Molecular behavior genetics is the study of the interaction between genes and the environment, and how that interaction affects behavior.

Determining heritability can point behavior geneticists in the right direction for their research.

Heritability - Key takeaways

  • Heritability is the statistical measurement of how genes influence the individual variations observed within a population. Heritability coefficient is a proportion used to quantify how much a trait or characteristic variation is due to genotype.
  • Heritability is not a measurement of how much genes and the environment influence a person's phenotype.
  • Heritability can also be a fluid measurement. It can increase or decrease based on the population that is being observed.
  • Identical twin studies allow researchers to "control" heredity. This is has led to many discoveries regarding heritability vs environmental impact.
  • If genes do not heavily determine the variation of a trait, it has low heritability. This means that environmental factors have the most significant impact on trait variability.

Frequently Asked Questions about Heritability

Heritability is the statistical measurement of how genes influence the individual variations observed within a population.

Heritability index is a proportion used to quantify the variation of a trait or characteristic due to a genotype. As a proportion, the numerical value of the heritability coefficient ranges between 0.0 and 1.0; 0.0 means no genetic influence, while 1.0 means entirely influenced by genetics.

Heritability is measured using the following formula, where Vg is the variation in genotype and Vp is the variation in phenotype:



The heritability coefficient is used for quantifying the variation of a trait or characteristic that is due to a genotype.

IQ is 50-70 percent heritable, while personality is 40-60 percent heritable.

Final Heritability Quiz

Question

How is the heritability coefficient calculated? 

Show answer

Answer

H2 = V/ Vp

Show question

Question

Heritability identifies a specific gene that is affecting phenotypic variation. True or False?

Show answer

Answer

False

Show question

Question

Which of the following is not considered to have high heritability?

Show answer

Answer

Walking

Show question

Question

If intelligence has a heritability of .60, what does this mean? 

Show answer

Answer

Genetics account for 60% of the phenotypic variation observed in intelligence

Show question

Question

Fraternal twins share what percentage of their genetic makeup?

Show answer

Answer

50%

Show question

Question

Petrill (2003) found evidence to support that                of the IQ variation within a group is due to genes.  

Show answer

Answer

50%-70%

Show question

Question

What are the five main personality traits? 

Show answer

Answer

  • Extraversion-Introversion 
  • Neuroticism 
  • Conscientiousness 
  • Agreeableness 
  • Openness to Experience

Show question

Question

If the variation of a trait is not heavily determined by genes, it has low heritability. True or False?

Show answer

Answer

True

Show question

Question

Heritability can never be a fluid measurement. True or False?

Show answer

Answer

False

Show question

Question

How can you determine the proportion of environmental factors that affect the variability of a trait?

Show answer

Answer

Subtract the heritability coefficient from 1.0.

Show question

Question

As environment becomes more similar, heritability becomes a more primary explanation for variations in characteristics. True or False?

Show answer

Answer

True

Show question

Question

Johnson (2016) found that personality traits are ____ heritable.

Show answer

Answer

40-60%

Show question

Question

As heredity becomes more similar, environment becomes a less primary explanation for differences. True or False? 

Show answer

Answer

False

Show question

Question

The observable characteristics that we possess are collectively called a

Show answer

Answer

phenotype

Show question

Question

The study of the interaction between genes and environment and how that interaction affects behavior is called

Show answer

Answer

Molecular behavior genetics

Show question

Question

Fill in the blank: _________ refers to the genetic makeup of a person. 

Show answer

Answer

Genotype 

Show question

Question

True or False: Heritability is the statistical measurement of how genes influence the individual variations observed within a population.

Show answer

Answer

True 

Show question

Question

True or False: looking at a person's genetic makeup, we know that each parent passes down 100 percent of their genes to their offspring.

Show answer

Answer

False

Show question

Question

What is the relationship coefficient (%) between identical twins? 

Show answer

Answer

100%

Show question

Question

What is the relationship coefficient between full siblings? 

Show answer

Answer

50% 

Show question

Question

What is the relationship coefficient between half-siblings

Show answer

Answer

25%

Show question

Question

True or False: Heritability is expressed as a proportion, which we often refer to as the heritability coefficient.  

Show answer

Answer

True 

Show question

Question

Fill in the blank: If genes do not heavily determine the variation of a trait, it has ___  heritability.  

Show answer

Answer

low 

Show question

60%

of the users don't pass the Heritability quiz! Will you pass the quiz?

Start Quiz

Discover the right content for your subjects

No need to cheat if you have everything you need to succeed! Packed into one app!

Study Plan

Be perfectly prepared on time with an individual plan.

Quizzes

Test your knowledge with gamified quizzes.

Flashcards

Create and find flashcards in record time.

Notes

Create beautiful notes faster than ever before.

Study Sets

Have all your study materials in one place.

Documents

Upload unlimited documents and save them online.

Study Analytics

Identify your study strength and weaknesses.

Weekly Goals

Set individual study goals and earn points reaching them.

Smart Reminders

Stop procrastinating with our study reminders.

Rewards

Earn points, unlock badges and level up while studying.

Magic Marker

Create flashcards in notes completely automatically.

Smart Formatting

Create the most beautiful study materials using our templates.

Just Signed up?

Yes
No, I'll do it now

Sign up to highlight and take notes. It’s 100% free.