Forensic Psychology - 4. Biological Explanations: 2. Genetic Explanations

Question 1

What do genetic explanations propose?

Answer 1

Propose that one or more genes predispose individuals to criminal behaviour

Question 2

What is the main gene involved in the genetic explanation for crime?

Answer 2

The MAOA gene

Question 3

What do some people have which means that less MAOA is produced?

Answer 3

Some people have a low level variant of the MAOA gene called MAOA-(L)

Question 3

What does the MAOA gene produce?

Answer 3

Produces enzymes which breakdown neurotransmitters in the synapse (E.g. serotonin and dopamine)

Question 3

What can less MAOA production affect?

Answer 3

It can affect neurotransmitter levels (increases neurotransmitter levels as breakdown is reduced) which affects brain activity in important parts of the brain

Question 4

What parts of the brain can lowered MAOA production (MAOA-(L)) impact?

Answer 4

The amygdala
The prefrontal cortex

Question 5

What is the amygdala involved in?

Answer 5

Emotions and the fight or flight response

Question 6

What is the prefrontal cortex involved in?

Answer 6

Decision making

Question 7

What will happen if the amygdala is affected by differing neurotransmitter levels?

Answer 7

The individual may lack:
-sympathy
-remorse
-empathy
-guilt
-have no conscience

Question 8

What does a negatively impacted prefrontal cortex do to the person?

Answer 8

Causes them to act differently and maybe carry out crimes for a boost

Question 9

Result of increased serotonin

Answer 9

Lowered mood
Impulsive decisions

Question 10

Who did Brunner at al study?

Answer 10

28 males from a large Dutch family who were repeatedly involved in impulsively aggressive violent/sexual behaviour

Question 11

What did Brunner et al find about the impulsively aggressive men in his study?

Answer 11

Had abnormally low levels of MAOA in their brains

Question 12

What does Brunner et al’s study support?

Answer 12

Supports the role of MAOA in explaining crime

Question 13

Who carried out research on genetically engineered mice with low MAOA levels?

Answer 13

Cases et al

Question 14

What did Cases et al find about the mice with low MAOA levels?

Answer 14

As the mice got older, they demonstrated increased levels of aggression and were aggressive during mating

Question 15

Negative evaluation of Cases et al’s mice study

Answer 15

Mice and humans are physiologically different and so, although there seems to be a genetic basis for aggression in mice, it doesn’t mean that such findings can be generalised to humans
Animals don’t have a consciousness so therefore can’t exert free will

Question 16

What did Christiansen study?

Answer 16

A large sample size of over 3500 twin pairs in Denmark

Question 17

Results of Christiansen’s study

Answer 17

Concordance rate of criminal behaviour for MZ (identical) twins was more than double that of DZ (non-identical) twins amongst males and females in his study

Question 18

Positive evaluation of Christiansen’s study into twins in Denmark

Answer 18

Results suggest that there is an element of heritability to criminal behaviour

Question 19

Negative evaluation of Christiansen’s study into twins in Denmark

Answer 19

We would expect the concordance rates to be higher if offending behaviour was purely down to genetics

Question 20

Who conducted a study into separated identical twins?

Answer 20

Grove

Question 21

What did Grove study?

Answer 21

The genetic contribution to offending behaviour, using twins who had been separated shortly after birth and grew up in different environments

Question 22

How many MZ twin pairs did Grove study?

Answer 22

32

Question 23

What did Grove assess the twins on his his study of separated MZ twins?

Answer 23

Alcohol problems
Drug problems
Symptoms related to antisocial behaviour in childhood and adulthood

Question 24

Results of Grove’s study of MZ twins

Answer 24

Significant positive correlation between genetic influences and symptoms of childhood antisocial behaviour and adult antisocial behaviour

Question 25

What do Grove’s results indicate?

Answer 25

Indicate similarity in terms of antisocial behaviour among twins

Question 26

Positive evaluation of Grove’s study of MZ twins

Answer 26

Highlights that genetic factors have a contribution

Question 27

Diathesis-stress model

Answer 27

Someone may have biological tendencies towards criminality, but they will need some sort of environment trigger to actually become a criminal