Biological theories Twin and adoption studies Flashcards
What are monozygotic and dizygotic?
Identical twins —> monozygotic ~share 100% of DNA
Non-identical twins —> dizygotic ~share 50% of DNA
Evidence to support twin studies?
Christiansen Studied 3,586 pairs of twins
52% concordance rate (similarity rate) between MZ twins
Only 22% concordance rate between DZ twins
Another guy Raine found similar results with a 44% CR and 21.6% CR
If the adopted child portrays similar behavior to biological parents this means…
Behaviour is genetic
Down to nature
Criminality is inherited
If the adopted child portrays similar behaviour to adopted parents this means…
Behavior is learnt
Down to nurture
Criminality is a result of upbringing
How many adopted sons did Mednick study?
over 14,000 adopted sons criminal records
What did the results show if the son had criminal biological parents?
Son was over twice more likely to be criminal
What did the results show if the son had criminal adoptive parents?
Ut had less of an effect meaning not very likely
What percentage of biological siblings raised in different environments both had a chance of committing crime?
30%
What percentage of adoptive siblings raised in the dame environment had a chance of committing a crime?
8%
What are some strengths of adoption studies
Reliable- uses data from throughout the childs life rather than a short space of time
Accurate for a direct cause and effect as they isolate the influence of the environment and the genetics
They are the only studies which can find a direct comparison of nature and nurture
What are some weaknesses of adoption studies?
Not very representative- the adiption process is rare and a small sample
Not very ethical -Adoption process can be a distress for the adoptee and/ or biological parents
Hard to establish definite cause and effect- Children are rarely adoted immediately from birth so there still may be some influence from the environment
