Twin studies - Research methods Flashcards
Why are twin and adoption studies useful to study?
They’re ways to investigate the effects of nature and nurture on behaviour
What does nature refer to?
Biological causes for behaviour - means the influence of genes that have been inherited from biological parents
What does nurture refer to?
The environmental causes of behaviour - Means the importance of upbringing, regardless of who parents are
Why are twin + adoption studies always natural experiments?
Because the IV being investigated (whether ur biologically related to family or what type of twin u are) is a naturally occurring variable
How much of ur DNA comes from ur parents?
All of it, 50% from each parent
What % of DNA do identical twins share?
100% - also known as monozygotic twins, always same gender
What % of DNA do non-identical twins share?
50% - Dizygotic twins, can be diff genders
What are the 2 types of twins? And what do they mean?
Monozygotic (MZ) = Twins were conceived in a single egg which later splits
Dizygotic (DZ) = Twins were conceived when 2 or more eggs were fertilised at the same time
What statistic are twin studies measured with?
Concordance rate
Concordance = If 1 twin shows behaviour + other twin does too
Discordance = If 1 twin shows behaviour but other doesnt
What is the concordance rate of the MZ twins compared to?
Concordance rate of DZ twins
What is the interpretation of MZ concordance being significantly higher than DZ concordance?
Behaviour is partly due to nature (genetics)
What is the interpretation of MZ concordance being similar to DZ concordance?
Behaviour entirely due to nurture (upbringing) - since DZ twins arent identical
What is the interpretation of MZ concordance being 100%?
Behaviour entirely due to nature (genetics)
What is the interpretation of MZ concordance being significantly less than 100%?
Behaviour partly due to nurture (upbringing)
What does higher concordance mean?
More chance of genetic influence
