AC2.1 - Biological Theories, Evaluation, and Policies

what do genetic theories of crime suggest

that they are inherited

why are twin studies used

because they are a way of testing the genetic theory of criminality, focusing on offending rates of identical twins

what are monozygotic twins

Twins that came from one zygote, which separated into two. They share 100% of their DNA (identical twins)

what are dizygotic twins

Twins that came from two separate zygotes and share 50% of their DNA and so are genetically the same as siblings (non-identical twins)

what are concordance rates

the probability as a percentage that if one twin has the characteristic, the other will have that characteristic too

what concordance rate should MZ twins have

100%, or at least higher than DZ twins

Explain Christiansen’s study

in 1977 he studied 3586 twin pairs in Denmark. He found a 52% concordance rate with MZ twins. If one of the twins had a conviction, there was a 52% chance that the other twin would too. For DZ twins however, the CR was only 22%

Explain Johannes Lange’s study

in 1929 he studied 13 MZ twins and 17 DZ twins (much smaller study). found that 10 of the 13 MZ had both served time in prison, whereas only 2 of the 17 DZ had both served time

strengths of twin studies

Because MZ twins are identical, it’s logical to see if offending behaviours are

these studies give support to some genetic explanations. Ishikawa and Raine found a higher concordance rate for identical than non-identical twins

weaknesses of twin studies

if genes were the only cause of criminality, identical twins would show 100%, however studies shown only around half or less

higher CR may be due to sharing the same home, school, friends etc. this is environmental

parents treat identical twins more alike than they do non-identical twins, and they’re closer than NI, so may be influenced by the other’s criminal behaviour

impossible to isolate the causes as genetic or environmental

Explain the idea behind adoption studies

comparing adopted children to both their biological and adoptive parents. If the adopted child shares the same environment with their adopted parents, but the same genetics as their biological parents, the CR should match the biological parents if crime is genetic

Explain Mednick et al’s study and what does it suggest about criminality

studied data on over 14000 adopted sons in Denmark from 1924-1947

more likely to have a criminal record if birth parents also had one (20% CR)

smaller CR (14%) if their adoptive parent had a criminal conviction

this suggests criminality is more likely down to genetics than environments

explain Hutchings and Mednick’s study

They compared adoptees with and without criminal records. They found that adoptees with criminal records were more likely to have birth parents with criminal records, than those whose birth parents did not have criminal records

why is it important to know if the child was adopted soon after birth or not

because the environment would have already started to socialise that child before they were taken from the biological parent

strengths of adoption studies

Overcomes the problems faced by twin studies, where biologically identical twins are brought up in the same household, making it impossible to separate influences of genes from environment. this is because they are brought up in a different environment to their birth environment

Research is logical and allows us to see the relative importance of nature vs nurture

The findings give support to genetic explanations. They do show that adoptees were more likely to have criminal records if their birth parents did

weaknesses of adoption studies

Gottfredson and Hirschi argue that adoption studies show genes have little effect on criminality

adopted children are often placed in similar environments to those of the birth family, such as the same class/ethnicity/same locality etc. same environment may produce similar behaviours

Many children are not adopted immediately after birth but remain with their biological family for some time. The early environment may be the true cause of their criminality

Explain Jacob’s XYY study

in some males there is a genetic abnormality where 2 Y chromosomes are inherited, which is known as Supermale/XYY syndrome

characteristics of men with this syndrome are tall, well-built, and low intelligence. Jacob says they could be more aggressive

what evidence is there to support Jacob’s XYY study

studies of imprisoned criminals such as psychiatric hospitals where higher proportions of the males were found to have XYY

he found that XYY men were over-represented in prison. 15 in 1000 men had XYY in prison. 1 in 1000 in the general population

strengths of Jacob’s XYY study

association between XYY syndrome and offenders imprisoned for violence. 15/1000 vs 1/1000

Price and Whatmore found property crime and XYY links

Alder et al indicated violent and aggressive behaviour can be caused by genetic factors

weaknesses of Jacob’s XYY study

even if violent offenders have XYY it’s not proof of cause

XYY males are strong, and fit stereotypes of violent offenders so are labelled by courts and more likely to get a sentence. Over-represented in prisons due to labelling not the increased likelihood of being an offender

may be over-represented due to low intelligence, so easily caught

syndrome is rare

Theilgaard (1984) researched traits and found aggression is not an XYY trait

What was Lombroso’s physiological theory of Born Criminals

he argued that criminals were physically different from non-criminals. He spent years measuring and recording details of the heads and faces of hundreds of prisoners

What were the characteristics that Lombroso identified as being criminal

1. enormous jaws

2. high-cheek bones

3. handle-shaped jaws

4. prominent eyebrow arches

5. exceptionally long arms

6. large eye sockets

what specific criminals had what specific features

murders would have ‘aquiline’ noses like the beak of an eagle

thieves would have flattened noses

how did Lombroso see criminals

as atavistic. they were throwbacks to primitive socieities, underdeveloped, and stuck in an early stage of evolution. unable to contorl their impulses and had a reduced sensitivity to pain, arguing they were like savages and apes

What is atavistic

throwbacks to primitive society where they would have been normal. but in a modern society, they are underdeveloped and pre-social

how many skulls did Lombroso study on

3839, including 383 dead criminals

4 negatives of Lombroso study

correlation, lack of research, no control group, and it was biologically deterministic (no choice, free will, meaning it wasn’t their fault so in court you can’t use it as defence)

strengths of Lombroso’s Born Criminal study

1. was the first person to study crime scientifically, using objective measurements to gather evidence

2. research showed the importance of examining the historical and clinical records of criminals

3. his later work took into accounnt social and environmental factors, not just hereditary

4. Lombroso’s work shifted focus from punishment to preventing future crime, by saying they weren’t freely choosing to commit crime

weakness of Lombroso’s Born Criminal study

1. Research fails to support a link between facial features and criminality

2. Lombroso failed to compare his findings on prisoners with a control group of non-criminals

3. by describing criminals as ‘primitive savages’ Lombroso equates non-western societies with criminals. this is racist

What was Sheldon’s Somatotypes theory

he argued that certain body types (somatotypes) were linked to criminal behaviour

what were the three somatotypes

ectomorphs, endomorphs, and mesomorphs

characteristics and personality traits of ectomorphs

• thin and fragile, lacking fat and muscle, flat chested, narrow hips and shoulders, thin face and high forehead

• self-conscious, fragile, inward looking, emotionally restrained and thoughtful

characteristics and personality traits of endomorphs

• rounded, soft, and tend to be fat, lacking muscle or tone, wide hips

• personality is sociable, relaxed, comfortable and outgoing

characteristics and personality traits of mesomorphs

• muscular and hard-bodied, very little fat, strong limbs, broad shoulders, and narrow waists

• personality is adventurous, sensation-seeking, assertive and domineering, and they enjoy physical activity

what did Sheldon argue

that mesomorphs were most likely to commit a crime. They are more likely to be attracted to the risk-taking and excitement of crime. Able to use their physical assertiveness over others, which can explain their involvement in crimes such as assaults

Who proved that brain injuries can link to criminal behaviour and what happened

Phineas Gage was working with dynamite when it blew up too close to him. This sent a 3 foot, inch thick metal rod into his head through his brain, damaging his frontal lobe. His pre-frontal cortex was damaged, with this region of the brain implicated in personality changes and violence/aggression

How did his brain injury link to cirminal behaviour

after the accident his personality changed entirely. he became anti-social, bad-mouthed, and got into fights and assaults

what was the epidemic in the 1920s that linked to impulsiveness, arson, and abnormal sexual behaviour

Encephalitis Lethargica among children

general criticisms of biological theories

• Environmental Factors Are Ignored (people might need a trigger to actually commit a criminal act, regardless if a person’s biology might make them)

• Sample Bias (researchers use convicted criminals, ergo not representative of criminals that got away)

• Crime Is A Social Construct (how can you be biologically inclined to commit crime when society itself determines what is criminal?)