Chapter 6 - Genetics

Question 1

What is the Human Genome?

Answer 1

-genome: the complete set of genes of an organism
-contains 30,000-80,000 genes on 23 pairs of chromosomes
-Human Genome Project: sequence entire human genome
-small number of genes are different for different individuals

Question 2

What do behavioural geneticists look at?

Answer 2

-behavioural geneticists attempt to determine the degree to which individual differences are caused by genetic and environmental differences

Question 3

What is highly controversial about genetics and personality?

Answer 3

-ideological concerns (no room for change if someone’s personality is based on genes)
-concerns about renewed interest in eugenics

Question 4

What are the 3 goals/things behavioural geneticists want to determine?

Answer 4

1. Percentage of individual differences in a trait that can be attributed to genetic difference
2. Ways in which genes and environment interact and correlate with each other to produce individual differences
3. Where in the “environment” environmental effects exist

Question 5

What is Genotypic variance?

Answer 5

-individual differences in the total collection of genes possessed by each person

Question 6

What is Phenotypic variance?

Answer 6

-observed individual differences, such as height, weight, or personality

Question 7

What is Heritability?

Answer 7

-proportion of phenotypic variance that is attributable to genetic variance

Question 8

What is Environmentality?

Answer 8

-proportion of phenotypic variance that is attributable to environmental variance

Question 9

What are Epigenetics?

Answer 9

-the effect of environment on gene expression
–silent gene becomes expressed
–expressed gene becomes silenced

Question 10

What are some misconceptions about heritability?

Answer 10

-cannot be applied to single individual
-not constant
-not a precise statistic

Question 11

When is the Nature-Nurture debate relevant?

Answer 11

-no debate at the individual level (always both)
-influence of genes and of environment is only relevant for the discussion of group-level variation

Question 12

What do family studies look at?

Answer 12

-correlates the degree of genetic overlap among family members with the degree of similarity in personality trait

Question 13

What does it mean if a trait is highly heritable (family studies)?

Answer 13

-family members with greater genetic relatedness should be more similar to one another on the trait than family members who are less closely genetically related

Question 14

What is the problem with highly heritable traits in family studies?

Answer 14

-members of a family who share the same genes also usually share the same environment
-confounds genetic with environmental influences

Question 15

What are the 2 types of twins and how many genes do they share?

Answer 15

-identical = monozygotic (mz): share 100% of genes
-fraternal = dizygotic (dz): share 50% on average, same as regular siblings
-Falconer’s Formula: heritability2 = 2(rmz-rdz)

Question 16

What are the 2 assumptions of the twins method?

Answer 16

1. Equal environments
2. Representativeness

Question 17

What did adoption studies look at?

Answer 17

-examine identical tw2ins raised together and apart
-explores whether characteristics are more influenced by heredity or environment

Question 18

What are the 2 theories of adoption studies?

Answer 18

-if personality variation is due to genetics, twins raised apart should be similar
-if more personality variation is due to family environment, twins raised apart should be different

Question 19

What were the findings of the adoption studies?

Answer 19

-positive correlations on traits between adopted children and adoptive parents provide evidence of environmental influence
-positive correlations between adopted children and genetic parents provide evidence of genetic influence

Question 20

What are the issues with the adoption studies?

Answer 20

-assumption that adopted children and their adoptive and genetic parents are representative of the general population - questionable
-problem of selective placement of adopted children (similar/opposite households)

Question 21

Why can siblings be so different?

Answer 21

-genetics: siblings share only 50% of genes on average
-contrast effect: children try to be different from siblings
-birth order effects: each child experiences parents differently

Question 22

What are the 3 areas of major findings from behavioural genetic research?

Answer 22

-personality traits
-attitudes and preferences
-drinking and smoking

Question 23

What are the major findings in personality traits?

Answer 23

-heritability estimates for major personality traits (Big 5) of about .20-.45
-some studies suggest as high as 48% across all 5 traits
-stability of these traits

Question 24

What are the major findings in attitudes and preferences (Minnesota twin study)?

Answer 24

-wide variance in heritability of attitudes
-some attitudes show high heritability (ex: traditionalism = .60)
-average age of ample = 41
-social attitude, intelligence, etc. were similar in twins seperated

Question 25

What are the major findings in drinking and smoking?

Answer 25

-behavioural manifestations of personality traits (sensation seeking, extraversion, neuroticism)
-drinking alcohol and smoking cigarettes are stable over time (meaning its genetic)
-both show evidence of heritability (alcoholism ~50%, smoking 40-60%)

Question 26

What percentage of personality traits are heritability and environmentalism?

Answer 26

-personality characteristics show heritabilities in 30-50% range
-hence, showing substantial degree of environmentality (in 50-70% range)

Question 27

What are the 2 key types of environmental influences?

Answer 27

1. Shared: in family environment, features of the environment shared by siblings (books at home)
2. Nonshared: in family environment, features of the environment that differ across siblings (friends, teachers, romantic partners, bullying)

Question 28

What is genotype-environment interaction?

Answer 28

-differential response of individuals with different genotypes to the same environments
-e.g., task performance of introverts versus extraverts in quiet versus noisy conditions

Question 29

What is genotype-environment correlation?

Answer 29

-differential response of individuals with different genotypes to different environments
-genotype-environment correlations can be positive or negative

Question 30

What are the 3 types of genotype-environment correlations?

Answer 30

1. passive
2. reactive
3. active

Question 31

What is Passive genotype-environment correlation?

Answer 31

-parents provide both genes and environment to children, yet children do nothing to obtain that environment (no control over what exposed to)
-child’s verbal ability and the number of books in home

Question 32

What is Reactive genotype-environment correlation?

Answer 32

-parents (or others) respond to children differently depending on the child’s genotype
-baby’s liking for cuddling and the mother’s cuddling behaviour

Question 33

What is Active genotype-environment correlation?

Answer 33

-person with particular genotype seeks out a particular environment
-high sensation seekers expose themselves to risky environments (their choice)