Genetic Theories Flashcards
What study did Jacob’s conduct?
Conducted a study on over 300 inmates and patients at a Scottish maximum security hospital - defined as ‘mentally subnormal males with dangerous, violent or criminal natural tendencies’
What were the findings of Jacob’s study?
1 in 28 of participants had the XYY chromosome
What are the strengths of Jacob’s theory?
Research support - 1 in 28 had the XYY chromosome
Price and Whatmore found a link between property crime and the abnormality
Real life application - Arthur Shawcross
What are the limitations of Jacob’s theory?
Syndrome rare - 1 in 1000 have the XYY chromosome, can’t explain all crime
Reductionist
What study did Christiansen conduct?
Studied over 3500 twin pairs in Denmark and accessed their criminal backgrounds
What were the findings of Christiansens Study?
52% of the time if an Identical twin was a criminal then the other twin was as well
22% of the time if a non-identical twin was a criminal then the other twin was
This criminal link was also found for property crimes (theft)
What are the strengths of Christiansens theory?
Reliability- Ishikawa and Raine had found there were higher concordance rates between identical twins than non identical
Research support- Christiansen, twin pairs in Denmark
What are the limitations of Christiansens theory?
If genetics were the true cause of crime - concordance rates for identical twins would be 100%
Reductionist
What study did Mednick conduct?
Studied 14,000 Danish Adopted Sons and made comparisons between them and their adoptive + biological parents
What were the findings of Mednicks study?
There was a 20% concordance rate between boys having a criminal record and their biological parents having one
14.7% concordance rate between boys having a criminal record and their adoptive parents having one
There is also a 20% concordance rate of crime between biological siblings living with different adoptive parents
What are the strengths of Mednicks study?
Research support - Mednick, 14,000 Danish adopted sons
Takes into account the environment (not reductionist) - 20% concordance between siblings with different adoptive parents
What are the limitations of Mednicks study?
Information on adoptive parents may not always be available - unable to compare
Early environment before the child is adopted may influence their behaviour
Adoption process - not always random, child may be placed with parents similar to their biological ones
