Aggression- genetic explanations

Question 1

Why are twin studies used when investigating genetic explanations?

Answer 1

MZ twins share 100% of their DNA and they not only provide a control sample for each other but can be compared to DZ twins

Question 2

What do twin studies conclude?

Answer 2

-If MZ twins are more similar in terms of aggressive behaviour it should be down to genes rather than the environment as they both share the same environment

Question 3

Why are adoption studies used?

Answer 3

-Highlight differences between biological and adoptive parents and their children
-Assess to what extent the environment and genetics influence behaviour

Question 4

What did Foccrara et al find in his study on MZ and DZ twins?

Answer 4

-For aggressive behaviour (physical assault) concordance rates of 50% for MZ twins and 19% for DZ twins)
-For verbal aggression the rates were 28% for MZ and 7% for DZ twins

Question 5

What was the procedure for Rhee and Waldmans study?

Answer 5

-Meta analysis study of 52 twin and adoption studies

Question 6

What did Rhee and Waldmans study conclude?

Answer 6

Environmental factors can only be an explanation for aggression if the specific genetic factors are already present

Question 7

What does the MAOA gene stand for?

Answer 7

monoamine oxidase gene

Question 8

What is the role of the MAOA gene?

Answer 8

Regulates key neurotransmitters, particularly serotonin

Question 9

Does the low activity form produce more or less of the enzyme?

Answer 9

Less

Question 10

What does a dysfunctional MAOA gene lead to?

Answer 10

An imbalance of serotonin and, possibly, to an increase in aggression

Question 11

What was the procedure of Brunner et al study?

Answer 11

-Study of 8 men from a Dutch family
-studied them because they showed high levels of impulsive aggression
-Assessed them using IQ tests + physical examination
-Interviewed the family members about their behavioural characteristics history

Question 12

What were the results of Brunner’s study?

Answer 12

-Abnormally low levels of MAOA gene which was later found to be defected
-Displayed aggressive and criminal behaviour
-Positive correlation between defected MAOA gene and aggressive behaviour

Question 13

Give a positive of Brunner’s study

Answer 13

High validity-multiple types of data involved

Question 14

Give 3 limitations of Brunner’s study

Answer 14

-Correlation does not mean causation
-Poor population validity
-IQ (intelligence) does not ink to aggression

Question 15

What did research such as Frazzeto et als study conclude?

Answer 15

A faulty MAOA gene alone is not enough to produce aggressive behaviour, rather it is the combination of a traumatic childhood with the faulty gene that is responsible for extreme aggression

Question 16

What is a limitations of Frazzeto et als study?

Answer 16

-Androcentric- only used male participants, poor generalisation

Question 17

Give an evaluation point (Reductionist)

Answer 17

-Reductionist
-There is an overemphasis on genetic element
-Not enough emphasis on the influence of the environment
-Fredette et als study found that people with trauma have more aggressive tendencies
-They found that a faulty MAOA gene alone is not enough to produce aggressive behaviour and that a combination of childhood trauma in combination with the faulty gene is responsible for extreme aggression
-May also be other genes involved
-Correlation does not mean causation

Question 18

Give an evaluation point (External reliability)

Answer 18

-Brunner et al: Studied the men in the family who displayed impulsive aggression and had committed crimes such as rape and arson
-Assessed them using IQ tests (although it could be argued that intelligence is not related to aggression), physical examinations and interviews with other family members
-They had abnormally low levels of MAOA, a gene later found to be defective
-Suggests that genes do play a role in aggression but these are findings from one family and this makes it difficult to generalise the conclusions due to low population validity

Question 19

Give an evaluation point (problems with assessing aggresion)

Answer 19

-Many studies on aggression rely on parental or self-reports of aggressive behaviour, whereas other studies have used observational techniques
-Miles and Carey meta-analysis study on 24 studies (twin and adoption)
-Provided support for the genetic explanation
-However other studies were greatly influenced by the mode of assessment which was heavily based on parental or self-reports. When observational ratings were used which would arguably be more objective, they found significantly less genetic contributions and a greater environmental influence. These inconsistencies in findings make it difficult to draw any conclusions on whether it is genetics or the environment influencing aggression.
-Lacks internal validity

Question 20

Give an evaluation point (Tiihonen- Finish prisoners)

Answer 20

Evidence supporting the MAOA-L gene causing aggression comes from Tiihonen et al (2015). Studying Finnish prisoners they found the MAOA-L gene alongside another gene CDH13, was associated with extremely violent behaviour. These genes were not evident in non-violent offenders suggesting it could be attributed to violence only supporting the role of genetics influence aggression. However critics argue that although this may make it difficult for people to control violent urges, it does not necessarily mean they will definitively show violent behaviour. Also these findings are merely correlational and due to this we cannot be sure of cause and effect for certain but merely a relationship exists between aggression and these genes being present. This may mean there is a third unknown variable that lays in between or that the environment and learning activates these particular genes in people over time. Furthermore the sample itself was only comparing Finnish people and this comparison and its findings may not generalise to other cultures making the findings culturally biased.