Genes and the Environment Flashcards
Critically discuss the use of twin and adoption studies to assess the relative contributions of genetics and the environment to development
Intro: what is a twin study/adoption study? both valid in assessing development - both benefits - both useful in eliminating factors from developmental equation
Main Body:
Twin studies - Fraga et al., 2005 - importance of genetics as 2 identical genes in shared environment can see natural variables changing outcomes - matched pairs design so allow optimal estimation of genes - Wilson, 1987 - ISSUE: assumption of shared environment
Adoption studies - Palmer and Hahn, 2011 - ISSUE: results may not be generalisable
Both - Rhee and Walkman, 2002 - studies not perfect in showing each factor influence but show contributions in different settings - in particular as no variables are manipulated (natural setting)
Both - don’t take into account complications (i.e. maltreatment) - Caspi, 2002
Conclusion: the limitations don’t negate the usefulness
We’re a product of the interaction between environment and our genes. Discuss
Intro: genes hold code for specific traits - suggests that for some there is need for certain environments to trigger these genetic traits - epigenetics though to show this - nature/nurture arguments are naive - Dick, 2011
Main Body:
Classic experiment showing interaction = Tyron, 1942 - but effect could be eradicated, Cooper and Zubeck, 1958 -Weaver, 2004 (Gottlieb) also highlights interaction - environmental factors clearly influence how genes function - issue of extrapolation - but Caspi, 2002 found activation of aggression due to genes and environment interaction so results can be applied - may actually relate to how susceptible individuals are
Conclusion: increasing literature suggesting interaction - nature/nurture theories have less strength - we are a product of our interaction
Critically evaluate the theory that some people are more susceptible to environmental influences than others. What are the implications of this?
Intro: Belsky and Pluess, 2009 - different levels of susceptibility - early childhood experiences play major role - environment leads to range of outcomes - notion of passive genetic-environment interaction assessed as well as active g-e-interaction
Main Body:
Caspi, 2002 - genetic predisposition affects susceptibility
However, - may be susceptibility occurs through inherited traits leading to seeking specific environments (Jaffee and Price, 2008) - e.g. extroverts - questions direction of effect - highlights differences in susceptibility
Implications - those develop conduct disorder may be drawn to violent video games - may further aggression (Anderson and Bushman, 2001) due to desensitisation - vicious circle - implications for those with abusive pasts
Further support - Fraga et al., 2005 - despite common genotypes the environment affects phenotypic expression
Implications - children’s potential - canalisation - increase support children receive
Conclusion: really important to provide support for children - some are more susceptible to environments that others
Fraga et al., 2005
epigenetic differences in lifetime of MZ twin
MZ twins show differences in phenotypic expression
as MZ twins get older they show greater differences
could be due to environmental differences
shows usefulness of twin studies - identical genes and similar environments - can see effect of this environment
Wilson, 1987
used twin studies to assess hereditary influence on IQ
found genetic influences at 18 months affected similarity of MZ and DZ twins in terms of intelligence
highlights how twin studies can determine these influences
ISSUE: assumption of shared environment
Palmer and Hahn, 2011
adoption studies provide direct test of role of environment and genes in development
ISSUE: generalisability of results
Rhee and Walkman, 2002
meta-analysis of 51 twin and adoptions studies
familial influence, for both genetic and environmental factors, was lower for adoption studies than twin studies
results suggest that twin and adoption studies are not perfect in showing the influences
but they do enable us to see if there is an influence in different natural settings
Caspi et al., 2002
children exposed to maltreatment and with low MAOA expression more likely to develop conduct disorder
supports that genes influenced by environment
shows importance of interaction
the low MAOA made them more susceptible to the environmental influence of maltreatment
maltreatment can trigger a gene that moderates propensity for aggression
important implications for early childhood treatment
Tyron, 1942
bred 2 lines of rates - intelligent or dull
did this by assessing best and worst maze runners and breeding them according to this trait
clear differences in ability to maze run - clear genetic differences due to lab condition
Dick, 2011
important to note that neither factor is entirely independent in their work
not all environmental influences are entirely random
Cooper and Zubeck, 1958
were able to eradicate effect found by Tyron, 1942
done through provision of enriched environment
i.e. objects to explore and more social interaction
highlights how environment can aid genetics and increase development - interaction
Weaver, 2004
baby rats born with gene for resistance to stress
gene activated by mother licking and nurturing them (grooming)
without this grooming then the gene is not expressed
highlights that environment must work with genetics to aid development
can relate to humans? extrapolation? aggression?
Belsky and Pluess, 2009
propose that genetic differences lead to different levels of susceptibility to environmental cues
argue that early childhood experiences may lead to range of outcomes
Evo-bio theory
Research has supported this notion : highlighting parenting, child-care quality, life events and residence to all affect susceptibility
Jaffee and Price, 2008
may be that whilst susceptibility to environment occurs it does so through individuals actively seeking out specific environment - active genetic-environment interaction
e.g. extroverts seek out environments that enable them to express this trait thus cementing their extroversion more
Anderson and Bushman, 2001
meta-analysis measuring effects of exposure to violent games
measured aggressive behaviour, mood, thoughts, cooperation and physiological arousal
short-term exposure to violet video games correlated with increased aggression
- perhaps children that develop conduct disorder are drawn to violent games
