Genetic factors in aggression

Question 1

What are genetic factors?

Answer 1

Inherited factors that increase or decrease the likelihood of behaving in a particular way

Question 2

What is the concordance rate for aggression in MZ twins?

Answer 2

50%

Question 3

What is the concordance rate for aggression in DZ twins?

Answer 3

19%

Question 4

What do twin studies suggest about aggression?

Answer 4

It has a genetic basis as the MZ concordance rate is greater than the DZ concordance rate

Question 5

In the adoption study looking at aggression, how many adoptions were studied?

Answer 5

14000

Question 6

In the adoption study looking at aggression, what country was it conducted in?

Answer 6

Denmark

Question 7

In the adoption study looking at aggression, what were the findings?

Answer 7

A significant number of adopted boys with criminal convictions had biological fathers with convictions for violence

Question 8

In the meta-analysis of twin and adoption studies into aggression, how many studies were included?

Answer 8

24

Question 9

In the meta-analysis of twin and adoption studies into aggression, what were the findings? (2)

Answer 9

Genetics can count for 50% of the variance in aggression + age plays a big role

Question 10

What gene is associated with aggression?

Answer 10

The MAOA gene

Question 11

What is the MAOA gene responsible for?

Answer 11

Producing an enzyme called monoamine oxidase

Question 12

What does MAOA regulate?

Answer 12

The metabolism of serotonin in the brain

Question 13

What are the 2 MAOA alleles?

Answer 13

MAOA-h and MAOA-l

Question 14

Which MAOA allele is associated with aggression?

Answer 14

MAOA-l

Question 15

What are the 4 AO3 points of genetic factors in aggression?

Answer 15

1) Research support for the MAOA gene
2) Problems with sampling
3) Difficulties with establishing the role of genetics
4) Can explain gender differences

Question 16

In the MAOA family study, what nationality were the family?

Answer 16

Dutch

Question 17

In the MAOA family study, what was the behaviour of the males like?

Answer 17

Highly aggressive + violent

Question 18

In the MAOA family study, what crimes had some of the men been found guilty of?

Answer 18

Arson and rape

Question 19

In the MAOA family study, what was found about the males genes?

Answer 19

They had defective MAOA genes

Question 20

Which gene allele is prevalent in countries with a history of warfare?

Answer 20

MAOA-l

Question 21

What percentage of people in countries with a history of warfare have the MAOA-l gene?

Answer 21

66.6%

Question 22

What percentage of people in countries with no history of warfare have the MAOA-l gene?

Answer 22

33.3%

Question 23

Name the 3 main reasons why it is difficult to establish a link between genetics and aggression.

Answer 23

1) More than one gene contributes
2) Many non-genetic factors that influence the manifestation of aggressive behaviour
3) These influences may interact with one another

Question 24

Why is it an issue that research into the genetic factors in aggression are mainly focused on individuals convicted of violent crimes? (2)

Answer 24

1) Only a small minority of individuals who carry out violent attacks are convicted
2) Offenders designated as ‘violent’ on the basis of a court conviction are not necessarily the most serious, persistent offenders

Question 25

What can the MAOA gene explain?

Answer 25

Gender differences in aggression

Question 26

On which chromosome is the MAOA gene found?

Answer 26

The X chromosome

Question 27

How many X chromosomes do females have?

Answer 27

2

Question 28

How many X chromosomes do males have?

Answer 28

1

Question 29

Why are males more likely to express the MAOA-l gene?

Answer 29

As the Y chromosome has no homologous region

Question 30

Why are females less likely to express the MAOA-l gene?

Answer 30

As they have a second X chromosome, which may have a normal MAOA allele