AC2.1 Flashcards
Genetic theories
Genetic theories as an explanation for criminal behaviour emerged with modern criminology in the 1700’s.
Genetic theories
XYY theory
Jacobs et al 1965
This theory of criminality suggests that some crime might be attribute to a chromosomal abnormality.
XYY men, sometimes called super males, have been of interest of criminologists because of the suggestion that they are more aggressive and more inclined to be violent than males with a single Y chromosome.
The serial killer John Wayne gacy is said to have XYY syndrome. He sexually assaulted,tortured and killed at least 33 men in the USA
Genetic theories
Twin studies
Johannes Lange 1929
Mz have higher concordance than dz
Christiansen 1977
Concordance rates of 35% (mz) and 13% (dz)
Twin studies support the contention that a heritable trait may increase risk for criminal behaviour.
Identical twins are monozygotic share 100% of dna
Two separate eggs are dizygotic share 50% of dna
When both of the twins share a characteristic there is said to be a concordance rate
Genetic theories
Adoption studies
Hutchings and mednick 1975
High proportion of boys with criminal convictions had biological parents with criminal convictions
Mednick et al 1994 found significant correlation between the number of criminal convictions of the biological parents and their offspring
The underlying principle of adoption studies in explaining criminal behaviour is the comparison of criminals with both their biological and adoptive parents. Such studies look at the impact of nature on children who are raised by their non-biological parents.
Genetic basis of criminality- more like biological than adoptive parents
Environmental criminality- more like adoptive than biological parents
Physiological theories
These theories focus on a persons physical form as an indicator of criminality. The most widely known are those of lombroso 2006 and sheldon
physiological theories
cesare lombroso - ‘father of modern criminology’
what he suggested
he said that criminal is a seperate species, is between modern and primative humans. lombroso argued that a ‘born criminal’ could be determined by the physical shape of the head and face. he claimed that criminality was heritable and those wsho committed crimes had atavistic or primative features. examples:
large or forward projection of the jaw
high cheekbones
flattened or upturned nose.
physiological theories
cesare lombroso - ‘father of modern criminology’
what he did
he examined the facial and cranial features of 383 dead criminals and 3,839 living ones and concluded that 40% of criminal acts could be accounted for by ativistic charecteristics.
murderers- bloodshot eyes, curly hair
sex offenders - thick lips and protruding ears
besides physical traits lombroso said that there were other aspects of the born criminal including insensitivity to pain, using slang, tattoos and unemployment
physiological theories
william sheldon
what he suggested
sheldon advanmced a theory that shares with lomboroso’s principle the idea that criminal behaviour is linked to a persons physical form. he said that there was three fundamental body types or somatotypes:
endomorphic: (fat and soft) tend to be sociable and relaxed
ectomorphic: (thin and fragile) are introverted and restrained
mesomorphic: (muscular and hard) are more aggressive and adventurous
physiological theories
william sheldon
what he did
he conducted a meticulous examination of photographs showing front, side and back views of 4,000 scantily clothed men. sheldon used a correlation study, and found that many criminals prone to committing violent and aggressive acts were mesomorphic.
physiological theories
brain abnormality
raine et al 1994
several studies showed that damage to the pre-frontal cortex of the brain may cause individuals to an altered behaviour pattern. becoming more immature and having an increased loss of self-control as well a having an inability to modify behaviour.
use of PET scans to study brains of impulsive killers
phineas gage - iron rod through left frontal lobe he became extravagant anti-social and used bad language
physiological theories
neurochemical
scerbo and raine (1993)
what they suggested
the brains chemistry can be influenced by diet, for example food additives, pollution or hypoglycaemia (low blood sugar levels associated with forms of diabetes)
some studies show that low levels of seretonin are linked with higher aggression. seretonin regulates signals between neurons and is said to control a persons mood.
physiological theories
neurochemical
scerbo and raine (1993)
what they did
conducted a meta-analysis on 29 studies into anti-social adults and children, finding low levels of seretonin in all of them. control of seretonin levels by diet is possible, as some foods, inluding dark chocolatre and cheese can help raise seretonin levls.
people who take large amounts of steroids can become extrememly violent.
horace williams, american body builder, beat a man to death after taking 2,000 times the recommended dosage
