research methods: twin studies Flashcards
define ‘nature’
biological causes of behaviour, link to genes, inherited from parents
define ‘nurture’
environmental causes of behaviour, shows importance of upbringing
what do twin studies investigate?
the role of genes / nature
what do adoption studies investigate?
the role of environment / nurture
what % of DNA do MZ twins share?
100
what % of DNA do DZ twins share?
50
how are twin studies measured?
concordance rate
what does concordance show?
- agreement
- if it is 100, all behaviours are shared so is completely genetic
what does it mean if MZ concordance is higher than DZ?
genetic
what does it mean if MZ concordance is similar to DZ?
environment
3 characteristics of twin studies
- longitudinal
- primary data eg interview
- secondary data eg hospital records
strength of twin studies (ethics)
investigates a naturally occurring behaviour
weakness of twin studies (gen)
MZ twin may be treated more alike than DZ so nature and nurture cannot be separated
weakness of twin studies (gen)
- epigenetic modification
- some differences in MZ twins
- therefore never 100% concordance
weakness of twin studies (gen)
- twins unrepresentative
- 1.5% UK births twins, 0.5% MZ
- however, IVF treatments so twins increasingly available
