2. Nature and Nurture Flashcards
what is a sensitive period
Effects of environmental stimuli on the developing organism are stronger during certain periods of development:
periods inthe life of an organism during which certain experiences or conditions may exert disproportionate influence
provide an example of nature-nurture interactions
(genes + antisocial behaviour)
A gene x environment interaction can be denmonstrated by the link between the MAOA gene and anti-social behaviour
Low activity variant of this gene correlates with expression of anti-social behaviour (criminality & violence)…But relationship is mediated by environment: Criminality more likely in people with low-activity gene variant AND who were mistreated/abused as children
thus Anti-social behaviour more likely if have gene and environmental factor
How do nature & nurture work together? -aims of behaviour genetics
Behaviour genetics
Aims to identify/disentangle role of genetics from environmental inputs to behaviour – Studies suggest almost all psychological traits have some genetic-inherited component (Intelligence; personality; emotion; psychopathology)
Environment also important in expression of genes (phenotype)
what do Twin studies tell us about the role of nature
Comparisons between identical and fraternal twins tell us something about role of shared genetics beyond shared environment
Expect higher similarity between MZ if genetics involved
Differences between MZ must be environmental…
strengths/weknesseses of separation studies when studying twins
MZ twins reared apart (RA) – different environments mean that similarities must be down to shared genetics…
But – often not totally ’apart’ (e.g. different branch of same family)
Already shared same environment in utero
Adoptive families often selected for being similar, not randomly selected
what have studies from adoption studies found
adopted children
Share DNA but not environment with biological parents/siblings
Can ask which they are more similar to – biological or adoptive family
- Some results suggest stronger correlation in IQ with biological parents
But other studies show working-class children raised in middle- or upper-class families show higher IQ than parents – environment has a role
importnt findings of behaviour genetics
All psychological traits measured show substantial genetic influence
-No traits shown to be 100% heritable
-Heritability depends on many genes having small effects
-correlations between behaviour are often underpinned by genetics (e.g. a correlation between reading behaviour & IQ)
- Most measures of ‘environment’ may also include a genetic component (e.g. parenting style, reaction to child’s personality?)
example of heritability
GCSE results were 64% heritable, and 75% of that heritability was accounted for by genetic factors in nine domains such as intelligence, school/home environment, personality, health
