Behavioural Genetics
science of how genes & environments influence behaviour
Challenge in researching behavioural genetics
most families children raised by biological parents = difficult separate nature & nurture
2 solutions to research challenge in behavioural genetics
- adoption studies
- twin studies
Adoption Studies
adopted child more similar to biological parents = nature
adopted child more similar to adoptive parents = nurture
Twin Studies
MZ twins more similarity in behaviour = nature
MZ & DZ twins same amount of similarity in behaviour = nurture
Heritability Coefficient
how strongly differences among individuals related to differences among their genes (0-1)
3 Insights of Heritability Coefficient
- everything somewhat heritable, nothing completely heritable
- genes > shared family environments (importance)
- ongoing debate abt which traits more vs less heritable
4 Caveats of Heritability Coefficient (HC)
- HC do not capture nature-nurture ratio
- HC say nothing abt HOW genes affect personality
- definition of environment vague/ overly restrictive
- HC partition variance into genes vs environment & negates gene-environment interactions
Gene-Environment Interactions
genetic differences affect behaviour under some environmental circumstances but not under others
4 laws of behavioural genetics (Chabris & Collegues, 2015)
- all human behavioural traits are heritable
- effect of raised in same family SMALLER than effect of genes
- substantial portion of variation in complex traits NOT ACCOUNTED by genes/family
- trait associated w/ many genetic variants, each account small % of behavioural variability
Genes work in ___ not ___ ways
probabilistic, deterministic
Evolutionary Psychology
understand traits through adaptive value promoting survival & reproduction
ancestral characteristics w/ more survival value are more likely appear in subsequent generations
