AC2.1 Biological Theories Flashcards
(38 cards)
What type of theory is Jacobs XYY?
Genetic
What is Jacob’s XYY theory?
Men with an extra Y chromosome are more likely to commit crime
What is the XYY syndrome also known as?
Super male syndrome
How does XYY syndrome occur?
It’s an error that occurs during fertilisation (it is not inherited)
What are the characteristics of XYY makes?
Increased levels of testosterone
Severe acne during adolescence
Often have learning disabilities/lower IQ
Slightly taller than average
Sometimes have minor behavioural problems
What happened during Jacob’s XYY study in 1965?
Patricia Jacobs examined 197 Scottish prisoners for chromosomal abnormalities using blood tests
Results suggested that men with XYY syndrome were more aggressive and potentially violent
How are XYY men over represented in the prison population?
For every 1000 prisoners, 15 suffer from XYY syndrome
For every 1000 people in the general population, 1 suffers from XYY syndrome
Who was John Wayne Gacey?
An American serial killer and rapist
He sexually assaulted, tortured and murdered at least 33 teenage boys and young men
It was believed he had XYY syndrome
What are the strengths of XYY syndrome?
Uses scientific methods
Real life application — study could help with potential treatments
Other studies have supported her claims (increases reliability)
What are the weaknesses of XYY theory?
There is conflicting research (decreases reliability)
XYY makes are so rare that it is hard to prove
Cannot establish cause and effect as subjects had other forms of medication
Relies heavily on genetics and ignores the behaviourist approach
Not very representative
What type of theory is twin and adoption studies?
Genetic
What do twin studies do?
Compare the likelihood of criminality between monozygotic and dizygotic twins
Why are twins a useful investigative sample?
They have the same upbringing and often similar social environments (useful for matched pairs design)
How much DNA do monozygotic twins share?
How much DNA do dizygotic twins share?
MZ=100%
DZ=50%
What was Christiansens study what did he find?
Twin studies:
Studied 3586 twin pairs in Denmark
He found a 52% concordance rate between MZ twins compared to only 22% in DZ twins
What do adoption studies do?
Compare adopted children to their biological parents and their adoptive parents to determine whether a behaviour/trait is down to nature or nurture
What does it mean if the adopted children portray similar behaviour to their biological parents?
The behaviour is genetic and down to nature
Criminality is inherited
What does it mean if the adopted children portray similar behaviour to their adoptive parents?
Behaviour is learnt and down to nurture
Criminality is a result of upbringing
What was Mednick’s study?
What were the findings?
Adoption studies:
He compared the data from criminal records of over 14,000 adopted sons in Denmark and compared the records with the biological and adoptive parents
He found that:
If the sons biological parents were convicted of a crime, they were more that twice as likely to be convicted themselves (adoptive parents convicted of crime had far less of an effect)
Biological siblings raised In different environments had a 30% chance of both committing crime
Adoptive siblings in the same environment had an 8% chance of both committing crime
What are the strengths of adoption studies?
Only type of study that finds a direct comparison between nature and nurture
Is images the influences of environment from genetics
Reliable as they can use data from throughout the child’s life
What are the weaknesses of adoption studies?
The process is not always random, children are often placed with parents similar to their biological families, this may influence their behaviour
May have ethical issues as it can be distressing for the adoptee and/or the biological parents
Difficult to truly separate genetics from environment as children are rarely adopted immediately so there is chance for environmental factors effect the child
May not be very representative as adoptions do not happen that often so there is a small sample
What type of theory is Lombrosos?
Physiological
What is a physiological theory?
A theory that focuses on a persons physical form and suggests certain features can be a sign of criminality
What did lombroso do?
Conducted post-mortems on the bodies of dead criminals and discovered distinct physical differences between the two
Argues that the head and face shape determined the ‘born criminal’
