PSYC 305 Chapter 6

genome

complete set of genes an organism has

genetic junk

the 98% of the DNA in human chromosomes that don’t code proteins

behavioural genetics

the study of genetic and environmental influences on behaviour

eugenics

the idea that the future of humans can be manipulated by reproducing certain traits and discouraging other traits

environmentalist view

belief that personality is determined by socialization

• eg: parenting style

percentage of variance

individual variability can be categorized into percentages based on to specific traits/variables

heritability

proportion of observed variance in people that can be explained by genetics

phenotypic variance

observable individual differences

• eg: height, weight, personality

genotypic variance

genetic variance responsible for individual differences in phenotypic expression of traits

environmentality

percentage of observed variance that can be attributed to environmental differences

• larger heritability = smaller environmentality

nature-nurture debate

discussion whether genes or environment is more important in determining personality

family studies

research correlating the degree of genetic overlap amongst family members with the degree of personality similarity

twin studies

research estimating heritability by measuring identical twins

equal environments assumption

assumption that identical twins experience environments that are no more similar than fraternal twins’ environments

• more similarity = could be due to more genes in common

adoption studies

research looking at the correlations between adoptive children and parents

• finding correlations in a trait provides evidence for environmental influences

selective placement

an issue with adoption studies

• when adoptive children are placed with parents who are similar to their biological parents, might increase correlation

• wouldn’t be able to separate environmental with genetic causes easily

shared environmental influences

features of the environment that siblings all share

• eg: number of books in a house, SES

nonshared environmental influences

features of the environment that siblings do not share

• eg: different friend groups

molecular genetics

techniques to identify which gene is associated with which trait

DRD4 gene

gene that responds to DA, activating other neurons

novelty seeking

associated with DRD4 gene, a trait involving seeking out new experiences (especially risky)

genotype-environment interaction

different responses of individuals with different genotypes to the same environments

genotype-environment correlation

the differences in exposure of individuals with different genotypes to different environments

passive genotype-environment correlation

when parents provide both genes and environment to the child

• but, the child did not do anything to obtain that environment

reactive genotype-environment

occurs when parents respond differently to children depending on each child’s genotype

• eg: one responds well to cuddles, other does not - parent stops cuddling the child that dislikes it

active genotype-environment correlation

occurs when a person with a particular genotype creates/seeks out a particular environment

• eg: a high sensation-seeker goes skydiving

epigenetics

study of how experiences determine whether a gene is expressed in an organism