Heritability and Genetics

Question 1

twins and adoption studies demonstrate

Answer 1

relative proportion of genetic and environmental influence on personality traits

Question 2

molecular genetic studies demonstrate

Answer 2

individual genes which influence personality

Question 3

additive genetic assumption

Answer 3

linear increase in trait similarity as proportion of genes shared by two individuals increases

Question 4

ways which additive genetics may be incorrect

Answer 4

genetic dominance- dz twins which share 25% wont be 50% less then mz
epistasis- traits from combination of genes

Question 5

equal environments assumption

Answer 5

similar shared environments of twins

Question 6

pleiotropy

Answer 6

effect of a gene on two or more phenotypic outcomes

Question 7

What is DNA comprised of

Answer 7

nucleotide base pairs (A,T,C,G)

Question 8

what do genes code for and where are its codes regions

Answer 8

code for proteins
exons

Question 9

what are alleles

Answer 9

specific form of a gene

Question 10

what is Single nucleotide polymorphisms (SNPs)

Answer 10

type of genetic variation- single base pair on the DNA strand

Question 11

Genotype

Answer 11

combination of different alternative forms of gene (alleles) possessed by an individual

Question 12

Phenotype

Answer 12

totality of observable traits and characteristics of an individual

Question 13

Heritability studies include

Answer 13

Family, Twin and Adoption studies

Question 14

Family studies

Answer 14

Genetic similarity decreases with distance from index case

Question 15

Heritability coefficient

Answer 15

proportion of variance attributable to genetic variation

Question 16

Trait heritability from twin and adoption studies

Answer 16

Bouchard-
personality 40%
Mental ability 20-80%
schizophrenia 80%
major depression 40%

Question 17

heritability estimates from twin and adoption studies

Answer 17

twin 40%
adoption 30%

Question 18

limitations of heritablity

Answer 18

shared environments not all equal
twin and adopted children not representative
genes + environment not operating independently

Question 19

3 main techniques of molecular genetics

Answer 19

Linkage analysis
candidate gene association
Genome-wide association

Question 20

Linkage analysis

Answer 20

used to study rare phenomenon this is simple and has a large effect size
marker genes used to indicate disease genes

Question 21

Candidate gene association requirements

Answer 21

hypothesis driven (knowledge needed) and large sample size and homogeneous (to prevent confounds)

Question 22

Candidate gene association

Answer 22

pick specific allele and compare cases to controls. Measure trait variation across genotype groups

Question 23

Candidate gene association example

Answer 23

lesch et al - serotonin linked to anxiety. 5HTT modulates. short allele associated with reduced 5HTT and increased anxiety

Question 24

Against candidate gene association

Answer 24

Munafo et al - initial finding not supported by further studies. suggesting other effects operating
any true effects of single genes likely to be minimal

Question 25

Genome-wide association requirements

Answer 25

Uses SNPs.
over 300,00 SNPs examined using DNA microarrays.
dose not require an hypothesis

Question 26

Evidence for genome wide association

Answer 26

Neuroticism- significant association of an SNP involved in bipolar, schizophrenia and depression

Question 27

Criticism of genome wide association

Answer 27

polygenic- traits shaped by large number of common alleles each having a small effect
large sample sizes required
meta-analysis uses may include difference in personality scales or properties (characteristics)

Question 28

Gene and environment studies

Answer 28

Caspi et al - 5HTT gene associated with neuroticism and depression
childhood trauma also associated
5HTT gene moderated effect of maltreatment leading to depression