Genetic Theories Flashcards
What are Monozygotic twins (MZ)?
Twins with the same genes (100%)
What are Dizygotic twins (DZ)?
Twins that are non-identical
What is Christiansen’s study about?
He studied 3586 twins pairs in Denmark. He found out that MZ twins have a 52% chance of the other twin also having a conviction
DZ twins have a 22% chance
What is the explanation of the adoptee being a criminal?
If the adoptee’s behaviour in terms of criminality is similar to the birth parents, this supports a genetic explanation. This is only if the environment for the adoptee was normal.
What did Mednick et al study about?
The examined 14000 adopted sons in Denmark. Found out that sons were more likely to have a criminal record if a birth parent also had a record, the concordance rate being 20%
What was another study by Mednick?
He compared adoptees with and without criminak records. The found out that adoptees with criminal records were more likely to have biological parents with criminal records than adoptees whose birth parents did not have criminal records
What was Jacob’s XYY study?
He found out that men who have XXY are more aggressive and violent, they also have low intelligence. Example would be John Wayne Gacy, the killer clown
What is the evidence for the Jacob’s study?
Studies on imprisoned criminals, such as those in psychiatric hospitals, a high proportion of the inmate were found to have the XYY gene
Price and Whatmore found XYY males to be immature and unstable
