Genetics and Personality

Question 1

what is behavior genetics?

Answer 1

Attempts to explain how personality traits that differ among individuals are passed from parent to child and shared by biological relatives
Examines how genes influence broad patterns of behavior Controversy lingers from eugenics and racism Controversies around biological determinis

Question 2

What is a genotype?

Answer 2

an individual’s actual genetic structure (your DNA)

Question 3

What is a phenotype?

Answer 3

The expression of a given genotype. Influenced by environment and experience (who you become)

Question 4

What are three traits related to behavior genetics?

Answer 4

Alleles, Autosomal and Polygenic traits

Question 5

What are polygenic traits?

Answer 5

polygenic traits and behaviors tend toward a normal distribution in the population, versus the either/or of autosomal traits

Question 6

What are Family Incidence Studies?

Answer 6

ID a proband with a trait and review frequency of that (and/or other) trait within the same family.

Question 7

Family Incidence studies have…

Answer 7

Higher incidence or shared ranges of a trait within a family (and decreasing incidence with genetic distance) suggests a genetic factor or relationship (sometimes a relationship between traits, e.g., different traits thought to be related, extraversion and openness)
Shared environment a confounding factor (Non-shared environment also a confounding factor)

Question 8

Monozygotic (MZ) twins are

Answer 8

(aka identical twins) come from a single egg and sperm: 100% shared DNA (they are clones!)

Question 9

Dizygotic (DZ) twins are

Answer 9

(aka fraternal twins) come from two different eggs and two different sperm: 50% (on average) shared DNA

Question 10

What is a question asked in twin studies?

Answer 10

are MZs more similar than DZs for a particular disorder (and usually how much more or less similar)?

Question 11

How are similarities measured in twin studies (Part one of two)

Answer 11

concordance rates if the trait is categorical (yes or no): if one twin has a trait, how often (what percent) does the other twin also have the same trait? (A concordance rate of 50% means half the time both twins have the trait.)

Question 12

How are similarities measured in twin studies (Part two of two)

Answer 12

correlation coefficients when the trait is continuous or dimensional (more or less, as with personality measures). Correlate scores (on the NEO-PI for instance) between twins.

Question 13

How do twins score in studies?

Answer 13

If MZs consistently higher, then a genetic component is presumed (assuming equal environmental effects). If a trait is completely genetically determined, then rates should be MZ: 100%; DZ: 50%

Question 14

What does it mean if the rates are high in twin studies?

Answer 14

If rates are high, and roughly equal, for both then shared environment is presumed influential

Question 15

What does it mean if the rates are low in twin studies?

Answer 15

Low rates for both implies effects of non-shared environment

Question 16

What are adoption studies?

Answer 16

Basic design is to compare those who were adopted as infants with their biological and adoptive parents and/or siblings
Sometimes compare twins adopted as infants (“reared apart”) to those who were not (“reared together”)

Question 17

What do rates mean in adoption studies?

Answer 17

If concordance rates are higher with bio parents than adoptives, biological factor is assumed; if reverse, then environment is accountable

Question 18

Why do we calculate heritabilites?

Answer 18

To examine how phenotypes may be attributed to variation in genotypes
Compare similarity in personality between people who are and are not related and people who are related to different degrees

Question 19

Monozygotic (MZ) vs. dizygotic (DZ) twins

Answer 19

• Assumption: Traits and behaviors influenced by genes should be more similar among more closely related people

Question 20

Concordance rates and the heritability quotient :

Answer 20

{rMZ –rDZ } X 2 (Makes some further assumptions) Average heritability coefficients for many traits for twins is
around .40, and from non-twin studies around .20
• Suggests that the effects of genes are interactive and multiplicative (and many traits are likely polygenic)

Question 21

What does heritability tell you?

Answer 21

Genes matter: not all of personality comes from experience
Etiology of disorders
Insight into the effects of the environment on personality development
Shared family environment does not seem to matter very much: The average correlation of personality for adopted siblings is only .05.
•Probably more accurate to say that non-shared family environment more important

Question 22

Heritability: Effects of parent training-

Answer 22

influences behavior and emotional control; affects aggression and personality measured with direct observation.

Question 23

Heritability: Based on behavior-

Answer 23

Shared family environment affects behavioral outcomes such as juvenile delinquency, aggression, and love styles

Question 24

Heritability: Research with self-reports-

Answer 24

People may focus more on traits that make them different from their siblings rather than on similarities.

Question 25

Heritability: technical issues-

Answer 25

similarity among adoptive families, same culture reduces variability; plus, adoption and its circumstances a confounding variable

Question 26

True or False: If there is a genetic influence, a trait (or other outcome) is inevitable

Answer 26

FALSE

Question 27

True or False:If a characteristic is genetically influenced, it cannot be modified

Answer 27

FALSE

Question 28

True or False:If there is a genetic influence, it must be directly responsible for behavior

Answer 28

FALSE

Question 29

True or False: genetics and environment are mutually influential

Answer 29

TRUE

Question 30

True or False: Genes interact with one another

Answer 30

TRUE

Question 31

How do you account for interactions?

Answer 31

Still difficult to statistically account for interactions; You can’t use heritability to determine what percent of a trait is determined by genetics and by the environment.
Traits with little variation will have heritabilities close to zero.

Question 32

There must be ______ in order for there to be ________

Answer 32

Environment, Behavior

Question 33

Genes are not causal:

Answer 33

they code for the material

Question 34

Next steps:

Answer 34

understanding how the development of specific aspects of the nervous system interacts with environmental experience to affect behavior; because genes and the environment interact

Question 35

Environments can affect heritabilities:

Answer 35

Nutrition and height (heritability will be higher when all children have the same level of nutrition, but lower when nutrition differs and therefore contributes differently to height); intellectual stimulation /educational opportunities and IQ

Question 36

Genetic expression and social environment:

Answer 36

height and teasing

Question 37

What are Gene-Environment Interactions

Answer 37

Choice of environment to be consistent with genetic
tendencies: sensation seeking and criminal environments
• The same environment can affect different individuals in different ways: responses to stressful or boring experiences
• Environments can determine how or whether a gene is expressed: A genetic predisposition for stress, anxiety, or aggression may only influence behavior in a stressful environment. The 5-HTT gene and culture

Question 38

What is epigenetics?

Answer 38

nongenetic influences on a gene’s expression
(stress, nutrition); experience, especially early in life, can influence how or whether a gene is expressed during development; most research has been with rats (stress response differs as a function of early maternal care)

Question 39

What is a Biological reductionism?

Answer 39

Everything about the mind can be reduced to biology.

Question 40

WILL BIOLOGY REPLACE PSYCHOLOGY?

Answer 40

We do not know enough about biology, but we do know that
the brain is “built” to interact with itself and with the world.
Biology leaves out most of psychology and does not ask many important psychological questions: What are people thinking? How are people influenced by the environment, including other people?

Question 41

How do genes effect behavior?

Answer 41

by influencing the propensities or tendencies toward certain behaviors.