biological theories: genetic

Question 1

What are the 3 physiological theories of crime?

Answer 1

Lombroso (atavistic)
Sheldon (somatotypes)
raine (brain abnormality)

Question 2

what are the three genetic biological theories of crime?

Answer 2

XYY (jacobs)
Twin Studies (Christensen)
Adoption Studies (Crowe)

Question 3

claims of twin studies

Answer 3

• Lange and Christiansen claim that criminality is a result of genes
• Christiansen and Lange said as twins have the same genetics either both twins will display aggression and criminal tendencies or neither will

Question 4

what are MZ (monozygotic) twins

Answer 4

come from one egg and one sperm these are identical twins they share 100% of their genes and are always the same sex.

Question 5

what are DZ (dizygotic) twins

Answer 5

come from two eggs and two sperm and so are non-identical this means they can be different sex. Their DNA is only as similar as that of any siblings they only share 50% of their genes.

Question 6

what is a concordance rate

Answer 6

percent of cases in which both members of a pair have a particular attribute. So, it is the extent to which both twins share the same characteristics.

Question 7

components of twin studies

Answer 7

Lange studied 30 pairs of twins (13 MZ twins & 17 DZ twins) found that 10/13 MZ twins had both spent time in prison whereas only 2/17 DZ twins had such concordance.

Christiansen did the same experiment in 1997, studied 3,586 sets of twins in Denmark he found a concordance rate of 35% in male MZ twins compared to 13% in male DZ twins and 21% In female MZ twins compared to 8% in female DZ twins.

Question 8

credibility of twin studies

Answer 8

(Scientific status) undertook scientific experiments, produced results that proved their theory

The experiment can be repeated, and the same results can be found

It assumed that each member of a twin pair is exposed to the same set of environmental influences regardless of zygosity

If the twins are brought up in the same environment, then criminality could just as easily be about environment as it is about genetics.

Question 9

applications of twin studies

Answer 9

Ronald and Reggie Kray were MZ twins, built a criminal empire in London throughout the 1950s and 1960s they were involved in armed robbery, arson, protection rackets, assaults, and murder. Their older brother Charles Kray was also a member of their gang never received the notoriety of Ronnie and Reggie. In 1997 Charlie was convicted of a 39 million cocaine smuggling plot and aged 70 jailed for 12 years.
Ronnie was eventually certified insane- his paranoid schizophrenia was treated with constant medication

Question 10

refuting evidence of twin studies

Answer 10

reductionist as don’t know what experience and exposure each twin has had

MZ twins look alike and may therefore generate more similar social responses than DZ twins this hasn’t been accounted for in theory studies.

The twin study result had a low percentage (concordance rate) only 35% for male MZ twins and only 21% for female MZ twins.

Critics of twin studies argue that they are based on false or questionable assumptions including that monozygotic twins are 100% the same DNA.

Question 11

supporting evidence of twin studies

Answer 11

Bouchard 1979 studied twins separated at birth found that identical twins who had different upbringings often had remarkably similar personalities interests and attitudes.

Lange and Christiansen concordance rates support each other’s study.

Question 12

claims of Jacobs XYY study

Answer 12

men with the XYY syndrome were more aggressive than normal XY men.

Question 13

components of Jacobs XYY study

Answer 13

Used a correlation study to compare men in prison to men in the general population to see how prevalent the XYY gene was.

There are 15/1,000 sufferers in prisons, 1/1000 sufferers in the general societal population

assumptions included that it made men more aggressive and antisocial and gave them below average intelligence

Accepted symptoms now included increased height a tendency towards delayed maturation being more physically active being prone to learning disabilities

Question 14

credibility of Jacobs XYY study

Answer 14

(scientific status) this theory has been studied extensively for 40-50 years

genetic difference had been identified that can be tested.

(reductionist)as it reduced criminal behaviour down to one explanation.

(deterministic)it implies that males with the extra y chromosome inevitably are more aggressive than males without it

Question 15

applications of Jacobs XYY study

Answer 15

John Wyne Gacy- said to have xyy syndrome. His killings were particularly violent. He sexually assaulted, tortured, and killed at least 33 men in the USA.

Richard speck- also said to be a ‘supermale’. Speck had a history of crime and violence but is known for killing eight student nurses. He broke into a building which was housing the women and stabbed and strangled 8 students after tying them up.

Question 16

supporting evidence of Jacobs XYY study

Answer 16

discovery by Ecole Rao of the turn syndrome supporting the idea that a chromosomal addition was possible.

In June 2002 the American journal of medical genetics compared xyy males with their xy siblings and found that the xyy siblings scored lower on the intelligence test.

Question 17

refuting evidence of Jacobs XYY study

Answer 17

theory focuses too heavily on genetic ignoring environment triggers, Richard speck was a degenerate alcoholic, this played more of a role in his criminality than xyy did

Genetic abnormalities are widespread and therefore do not explain aggression.

Question 18

claims of adoption studies

Answer 18

regardless of the changed environment, children seemed biologically predisposed to criminality

you can separate the nature/nurture influence by studying individuals that have been adopted at a young age by comparing their behaviour to the behaviours of biological and adopted parent we should be able to find out genes or the environment have a bigger influence.

Question 19

components of adoption studies

Answer 19

Crowe compared group of adopted children whose biological mother had a criminal record to a control group of adopted children whose biological mother who did not have a criminal record.

If biological mother had criminal record, 50% of adopted children had one by 18. The control group of children from non-criminal mothers only 5% of the adopted children had a criminal record by 18

regardless of the changed environment children seemed biologically predisposed to criminality.

Question 20

credibility of adoption studies

Answer 20

The results from the adoption studies do point to a significance of the genetic link between biological mothers’ criminality and adopted child’s criminality.

Adoption studies are on of the classic research methods of behavioural genetics and are on an effective technique for assessing the impact of genetics and environmental variables in shaping our behaviour

Sample sizes very small so may not be large enough

Many adopted children are not adopted at birth and their life experiences prior to adoption may significantly affect their later development

Question 21

refuting evidence of adoption studies

Answer 21

Age of adoption may mean the children have already been influenced by their biological parents or foster environment

need to consider the amount of contact with biological parents.

Doesn’t take into account the father’s criminal background.

Question 22

supporting evidence of adoption studies

Answer 22

Mednick et al 1994- compared court conviction of 14,427 adoptees with those of their biological and adoptive parents
Found a significant correlation between the number of criminal convictions of the biological parents and their offspring but non between adoptive parents and child, although this was only for property crimes not violent crimes.
Siblings adopted separately into different homes tend to be concordant for convictions especially if the shared biological father also had a record of criminal behaviour.