2.1 Biological Theories Of Criminaility-gentical Flashcards
What is the name for 100 percent identical twins
Monozygotic
What is the name for 50 percent identical twins
Dizygotic
Key idea of twin studies
If crime is genetic – identical (Mz)
twins should have identical criminality
What research supports twin studies
Johannes longe was a German physician he studied 13 pairs of identical twins 10 of those had both spent time in prison he studied 17 pairs of non identical twins and found out a greater proportion of MZ twins showed more criminal behaviour
More evidence to support twin studies
Christansen 1977
Studied 3500 sets of twins
Males=35% of MZ twins shared criminal characteristics compared to 13% of DZ twins
Females=21% of MZ twins shared criminal characteristics compared to 8% of DZ twins
Strengths of twin studies
Twin & adoption studies give some support to genetic explanations
Adoption studies overcome the problem of isolating genes and environment
Natural experiment as having twins is a natural variable
Christiansen 1977 supports the theory
Limitations of twin studies
If criminality was only genetic MZ twins would have 100% concordance.
It is impossible to isolate genetic effects fully from environmental ones.
Adopted children often placed with similar families to their birth family
If twins were brought up in the same environment criminality can be attributed to nurture rather than genetics
Explain the nature vs nurture debate
Whether a persons development,behaviour and personality is primarily shaped by there biological genetics or by there environment
How do adoptive studies work
Adoptions studies can be used to explain criminal behaviour adoptions studies help scientists if it’s nature or nurture
Researchers look at children who were adopted often at a young age and compare their behaviour with that of both their biological parents and their adoptive parents
Since the child shares genes with their biological parents researches can check whether there’s a pattern in criminals behaviour that appears in the biological family
What is the names which was a study on adoption studies
Hutchings and Mednick
adoptees aggressive behaviour correlates more with the biological parents than the adoptive parents = genetic influence applied
hitching and mednick = study on 14000 adoptees in Denmark, found significant number of adopted boys with criminal conviction had violent criminal convicted biological parents , provides evidence for genetic link
The study found that the biological father criminal behaviour had a stronger affect on the adopted sons likelihood of committing a crime even if the adopted parent had no such criminal record
Strengths of the adoption studies
Adoption studies overcome the problem of isolating genes and environment
Research design of Adoption studies is logical (nature vs nurture)
Easier to separate genetic and environmental factors as they are separated from there biological family
Studies show a correlation between a adopted children and there biological parents
Limitations of adoption studies
It is impossible to isolate genetic effects fully from environmental ones.
Adopted children often placed with similar families to their birth family
Age of adoption impact the study as they spent time with the family
What were men with extra Y chromosome referred to as
Supermales-XYY
What did criminologists believe about men with an additional Y chromosome
More aggressive and violent then men with one Y chromosome
Evidence and the name of person to support xyy theory
Jacob eat al 1965
He found that per 1000 males in prison 15 had the additional y whereas in the general population 1 in 1000 had the extra Y chromosome
What case study can be used to support Jacob et al
John Wayne Gary is an example of an offender has the additional Y chromosome he was a serial killer who sexually assaulted,tortured and killed at least 33 men in America
Strength of xyy theory
Jacob et al found association with
XXY and violent prisoners
Alder et al 2007 indicated that aggressive and violent behaviour can be determined by genetic factors
Limitations of xyy theory
Having the syndrome doesn’t mean that is the cause of crime
Xyy men fit stereotype of violent offenders - labelling theory
Syndrome is too rare to explain much crime
Focuses on genetics ignores other theories
Not all people with xyy are aggressive
Brian injuries- name the person who talked about PET scan and explain what he did
Used PET scans to study the living brains of killers and he found damage was found in the prefrontal cortex of the brain damage to this part can alter behaviour
Name of man which a rod went through his head
Phineas gage
What happened and who was he-phineas gage
A man working on the railroad in 1848 when he suffered a devastating brain injury
A pointed, 4ft rod went through his cheek and out his skull
The frontal lobe was affected.
The injury damaged the part of his brain where judgement and ability to make good decisions are located
More background and behaviour change on phineas gage
Phineas Gage, a railroad foreman, underwent a dramatic personality shift after an explosion drove a metal rod through his frontal lobe. Previously responsible and well-liked, he became irritable, rude, and socially inappropriate, losing his ability to hold a job. His employers and peers noted he was “no longer Gage.” This case became a key study in neuroscience, illustrating the connection between brain injury and personality changes. Though his personality gradually improved, Gage struggled to maintain steady work until his death 12 years later from a seizure linked to his injury.
Strengths of brain injury
A few extreme cases do show brain injury leads to changes in behaviour including criminality.
Prisoners are more likely than non-prisoners to have a brain injury.
There is some correlation between EEG readings and psychopathic criminality
Limitations of Brian injuries
Crimes caused by brain injury or disease are rare. Original personality more important.
Abnormal EEG not necessarily the cause and not found in all psychopaths
Prisoner’s higher likelihood of brain injury may be affect of criminality mot cause
