Behavior Genetics

behavior genetics
one way to examine personality and psychopathology relation while looking for empirical support; involves the nature/nurture contributions; goal is to understand how variability in an outcome of interest is attributable to genetic versus environmental factors

nature/nurture contribution
used a lot in behavior genetics; relative contributions of each are involved; not solely one or the other-more the question of the weight of each

behavioral genetic equation
r= relationship between two things
r= (h(x) * h(y) * r(genetics) + (e(x) * e(y) * r(environment)

behavioral genetics research
uses family studies (look at sibling relations and parent-child relations as 2 methods), adoption studies and twin studies; most commonly uses correlational techniques; looks for the heritability coeffiecient

heritability coeffiecient
usually the numerical result discussed in behavioral genetics; used to estimate the proportion (%) of observed variablity that is due to genetics

example of behavioral genetics results
when looking at agreeableness you see mono. twins are .9 and dy. twins are .6; see that nature makes fairly significant contribution to this trait

hypothesis related to behavioral genetics
-vulnerability/risk hypothesis
-common cause/spectrum hypothesis

vulnerability hypothesis and behavioral genetics
supports this hypothesis by using either the: 1. gene-environment correlation or 2. gene-environment interaction; these are not going against each other, can use both, depends on the disorder being observed

gene-environment correlation
says you’re born with a genetically-based trait, and that this trait influences the person’s environment in such a way that it promoted the development of a disorder; trait shapes your environment; nature causes nurture; three types (passive, reactive, active)

example of gene-environment correlation
1. very introverted>>create secluded lifestyle>>develop social phobia
2. high in sensation seeking>>live in urban area with more availability to illicit drugs>>develop substance use disorder

passive gene-environment correlation
born with certain trait and have the same trait as parents; they have created the environment for you

reactive gene-environment correlation
other people noticed trait about you and they encouraged you to continue to seek out those things

active gene-environment correlation
you purposefully structure environment in a certain way to back-up those traits

gene-environment interaction
says that the environment affects how genes are expressed >> certain environments might cause genes to be expressed in a way that causes disordered behaviors; environment >> turns gene on or off >> could activate a gene that causes disorder if extreme

gene-environment interaction example
trait: sensation seeking >> only becomes disorder if ones environment has illegal substances readily available
duke experiment: MAOA gene; having the gene is a risk factor for antisocial PD; more likely to become activated in abusive childhood experiences which leads to antisocial PD

gene-environment interaction in relation to common cause/spectrum hypothesis
whatever leads to development of the personality trait would lead to the disorder (if extreme enough) because they are on the same scale

gene-environment interaction in relation to scar hypothesis
psychopathology changes ones personality; ex: dementia, alcoholism, PTSD, evaluating this is empirically challenging because you need a longitudinal study to prove it

common pathways model
supports the common cause/spectrum model; says that you inherit one thing that determines where you fall on the spectrum

independent pathways model
supports the common cause/spectrum model; says that you inherit multiple things that determine where you end up on the spectrum