[GENETIC THEORIES] Biological Theories of Criminality Flashcards
XYY Theory [Chromosomal Abnormalities]
Explain the XYY ‘Super Male’ Theory
Jacob ET AL.
Some crime may be attributable to a chromosomal abnormality
Not inherited
extra Y chromosome
Males with the ‘Super male’ abnormality are known to be more aggressive as they have extra testosterone in the Y chromosome
XYY Theory [Chromosomal Abnormalities]
Explain three of the XYY traits
Delayed Speech development
Below average intelligence
Learning and behavioural problems
XYY Theory [Chromosomal Abnormalities]
Explain how the ‘Super Male’ syndrome may act on the brain
LIMBIC SYSTEM
(Controls out emotions and regulates male primitive desires)
Can lead to a male becoming more impulsive and more violent
This can trigger violent criminal acts
XYY Theory [Chromosomal Abnormalities]
Explain the research conducted
XYY men are over-represented in the prison population
350 men tested for XYY chromosome abnormality (Prisoners)
Only 9 men had the extra Y chromosome
XYY Theory [Chromosomal Abnormalities]
Explain 3 strengths
+ Scientific explanation/approach
+ Some cases where offenders have had an extra ‘Y’ (E.G: John Wayne Gacy)
+ Higher testosterone which is known to lead to higher violence
XYY Theory [Chromosomal Abnormalities]
Explain 3 weaknesses
- Not all ‘XYY’ super males are criminals
- Cant explain criminality in women (XX)
-Social and upbringing factors are ignored and only focus on biology
XYY Theory [Chromosomal Abnormalities]
Explain how the ‘XXY’ chromosomal abnormality causes criminality
Testosterone can lead to violence
[FAMILY STUDIES]
Explain the family studies theory
Looking at families to see if there’s a pattern of criminality to explain biological genetic reasons
Looks at similar behaviours between family members
Francis Galton: Looked at intelligence or genius and founds that this was hereditary
[FAMILY STUDIES]
Explain how this can cause criminality
If there is a pattern between family members and crime it can be suggested that there is a strong likelihood that crime is related to families - means criminality is due to genetics
[FAMILY STUDIES]
Explain a strength
- Shows a genetic predisposition
[FAMILY STUDIES]
Explain 3 weaknesses
- Ignores social factors
- We cannot separate the effect of genetics from the effect of the environment
- Although there is a correlation between criminality and family members, other factors in the environment (unemployment, poor education) could contribute
[FAMILY/TWIN STUDIES]
What are the two types of twins
Monozygotic
&
Dizygotic
[FAMILY/TWIN STUDIES]
Explain the two types of twins and behaviour as a result of genes
Monozygotic = Identical twins from one egg, shared DNA, same environment, Behave in a similar way
Dizygotic = non-identical, separate eggs, share 50% of DNA, same environment, same as an ordinary sibling
If behaviour is caused by genes - MZ twins should be more similar than DZ twins (Concordance rate - behaving in a similar way)
[FAMILY/TWIN STUDIES]
Explain the link to criminality
If both identical twins are criminal, this suggests a very strong link to criminality
[FAMILY/TWIN STUDIES]
Explain the supporting evidence for criminal concordance
Christiansen
Studied 3586 pairs of twins to identify higher concordance rates of criminal behaviour in MZ twins (theft, not violent crimes)
Results: MZ twins has a higher % than DZ twins
[FAMILY/TWIN STUDIES]
Explain why the twin studies are more useful than family studies
Takes the nature side of the debate into account and looks into the biology - how genetics have an impact on criminality
[FAMILY/TWIN STUDIES]
Explain 3 weaknesses
- We are still seeing impact of environment (nurture)
- small samples may not be representative
-in Christiansen’s study there is a difference in the % depending on gender, raising the question about how gender may affect criminal behaviour
[FAMILY/TWIN STUDIES]
Explain a strength
MZ shows higher rate of concordance than DZ, shows genetic similarity (E.G: The Krays)
[ADOPTION STUDIES]
Explain 3 strengths
+ Adoption studies make it easier to separate the nature/nurture debate
+ Studies show correlation between biological and adoptive parents
+ Mednick ET.AL. suggests both genes and environment are important but genes may be more significant
[ADOPTION STUDIES]
Explain 3 weaknesses
- Ages of adoption may mean adopted children have been influenced by their natural parents
- Adoption is not always random
- Practical issues = info about biological parents may not always be available for comparison
[BRUNNER SYNDROME - WARRIOR GENE]
Explain 3 strengths
+ Explains criminality in both men and women
+ It’s scientific - can identify if someone has a faulty gene (observable)
+ There is research evidence (Caspi and Brunner)
[BRUNNER SYNDROME - WARRIOR GENE]
Explain 3 weaknesses
- Not everyone with a faulty MAOA gene is aggressive or violent
- Cant ignore the role of the environment (Caspi)
- Small numbers of people within the population have this gene in comparison to those offences out there
[ADOPTION STUDIES]
Explain the Adoption Studies
Looks at the impact of nurture on children who are raised by their non-biological parents
If child is more similar to adoptive parents suggests nurture (environment) is more important
if more similar to biological parents, suggests the nature (genes) side is more important
(Are criminals born or made??)
[ADOPTION STUDIES]
Explain Crowe’s findings
if an adoptee’s biological mother had a conviction the adoptee had a 50% chance of having a conviction
If mother didn’t have conviction -child had 5% chance
(FEMALE FINDINGS)
[ADOPTION STUDIES]
Explain Mednick ET.AL
14,427 adopted sons
criminal records of both biological and adoptive parents
Compared adoptee’s criminal records with adoptive and biological parents
Sons were most likely to have criminal record if biological parents had one (20% concordance rate)
14.7% had criminal record if adoptive parents did
((Suggests that both genes and environment are important but that genes may be more important in explaining criminality))
[BRUNNER SYNDROME - WARRIOR GENE]
Explain the Warrior Gene theory
Looks into an association between gene and aggressive behaviour
[BRUNNER SYNDROME - WARRIOR GENE]
Explain having too much and too little of the MAOA gene
Too much = Little serotonin
Too little = Too much serotonin
[BRUNNER SYNDROME - WARRIOR GENE]
Explain Brunner’s research and findings
Study was done on Dutch family - defect in male family members (They were all very violent)
Blood samples were taken to isolate DNA
Mutation on the X chromosome and responsible for the production of the MAOA gene
Brunner found all members with this gene were aggressive when angry, fearful or frustrated
[BRUNNER SYNDROME - WARRIOR GENE]
Explain the MAOA gene
A faulty gene
produces an enzyme that control neurochemicals in the brain
One problem: The faulty gene can cause an over-production of the enzyme MAOA gene which breaks serotonin down too quickly
[BRUNNER SYNDROME - WARRIOR GENE]
Explain what can happen when serotonin is broken down too quickly and are low
makes communications between specific brain regions of the limbic system and frontal lobes weaker
can be more difficult for prefrontal cortex to control emotional responses
[BRUNNER SYNDROME - WARRIOR GENE]
Link to criminality
Overproduction of MAOA Gene =
Serotonin moderates impulsivity therefore chemical imbalances can cause anti-social behaviour and violence offending
Sluggish MAOA Gene =
Slows down the metabolism and serotonin and other neurotransmitters - leading to higher levels of serotonin, dopamine and norepinephrine which can lead to aggressive behaviour
[BRUNNER SYNDROME - WARRIOR GENE]
Explain what happens if the MAOA gene is sluggish
Slows down the metabolism and serotonin and other neurotransmitters - leading to higher levels of serotonin, dopamine and norepinephrine which can lead to aggressive behaviour
[BRUNNER SYNDROME - WARRIOR GENE]
Explain high levels of serotonin
Can cause aggression and cause people to feel less empathy for other and more willing to harm others
Brain cant cope with too much serotonin
[BRUNNER SYNDROME - WARRIOR GENE]
Explain caspi’s research and findings
Large group of individuals
Followed from ages 3-20
Looked for maltreatment between 3 and 11 yrs old
Looked at their genes
Looked at criminal record
Findings:
Maltreatment = significant predictor of aggression. low activity of MAOA
Maltreatment + low activity of MAOA = significant aggression
(Strongest predictor of behaviour - combination of factors)
[BRUNNER SYNDROME - WARRIOR GENE]
Who is the MAOA gene inherited from?
The mother - X chromosome
[BRUNNER SYNDROME - WARRIOR GENE]
Explain why MAOA gene has more impact on men
Men have higher levels of testosterone
What are all the Genetic Theories?
XYY ‘Super male’ - Jacob Et At.
Family Studies
Twin Studies
Adoption Studies
Warrior Gene - Brunner
