research methods: twin studies Flashcards
(20 cards)
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
- the probability of one twin sharing a certain characteristic of the other twin
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 (validity)
- MZ twin may be treated more alike than DZ so nature and nurture cannot be separated
- therefore treated more alike which may lead to researcher bias in their concordance rate.
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
- therefore, it is unrepresentative of the wider population
- additionally, twins may experience unique social environments- such as being treated as more alike by getting more parental attention or comparison- so cannot generalise the results from twins to children who have grown up without a twin- with a different family structure
weakness of twin studies (validity)
- allocated into MZ DZ (zygocity) by physical appearance
- therefore, may be inaccurate, reducing internal validity of results
- BUT- uses scientific measures such as genetic testing to check the presence of a gene, so scientific methods allow for validity
strength of twin studies (application)
- studies tell us whether important behaviours are heritable
- treatments and alert parents to children at risk
- influence early intervention by investigating if a behaviour is genetic- if it is, then genetic testing can be done to determine those at risk and implement strategies to combat this
weakness of twin studies (deterministic)
- no free will
- but never 100% concordance
- twin studies may show influence of genetics but no account for nurture
What methods may a twin study use?
- DNA sampling
- questionnaires
- interviews
- psychometric testing
Strength of twin studies- validity
- MZ twins share 100% of DNA
- so comparing them with
