Aggression Booklet 2: Genetic explanations

Question 1

What are the basics of the genetic explanation?

Answer 1

-Some scientists believe aggression can be inherited through genes
-This is investigated through twin and adoption studies

Question 2

Why do we use twin studies?

Answer 2

-By looking at twin studies we can examine twins raised together in the same environment
-By looking at MZ and DZ twins we can see whether genetics play a role in aggression, since DZ share 50% and MZ share 100%
-Therefore a higher concordance rate with MZ twins indicates a genetic basis

Question 3

What do 4 different concordance rates indicate?

Answer 3

-MZ twins have 100% concordance rate: behaviour purely genetic
-MZ twins have concordance rate less than 100%: behaviour must be at least partly down to environment
-MZ twins have significantly higher concordance rate than DZ twins: Behaviour must be at least partly down to genes
-MZ twins and DZ twins have similar concordance: Behaviour must be down to environment

Question 4

What study is used for AO1 twin studies research in aggression?

Answer 4

Coccaro

Question 5

What was found in Coccaro

Answer 5

-Studied adult male MZ and DZ twins for aggressive behaviour
-Found that concordance rate for MZ twins 50% compared to 19% DZ twins

Question 6

What do the results of Coccaro demonstrate?

Answer 6

-Showed that genetics do play a role in aggression as those more genetically similar are more likely to be aggressive compared to hose less genetically similar

Question 7

What can you talk about in AO1 twin studies for bonus marks?

Answer 7

EQUAL ENVIRONMENTS ASSUMPTION

Question 8

What is the issue: equal environments assumption

Answer 8

Studies assume both MZ and DZ twins share an environment 100% the same, isn’t necessarily true since they will share different interests personalities and friends etc.

Question 9

Why can we use adoption studies?

Answer 9

-By looking at adoption studies, allows us to look at children adopted to see whether more similar in terms of aggression to biological or adoptive parent
-Allows us to see which is more important: genetics or environment

Question 10

What is the main research study for adoption studies?

Answer 10

Mednick, Gabrielli and Hutchings

Question 11

What was found in Mednick, Gabrielli and Hutchings?

Answer 11

-Carried out adoption study over 14000 participants
-Researchers studied criminal records of all children adopted outside biological family between 1924 and 1947
-Found that having a criminal biological father increased risk of child’s criminality and aggression more than having an adoptive criminal father

Question 12

What did the findings of Mednick, Gabrielli and Hutchings show?

Answer 12

It showed that genetics are a factor influencing aggression, as even under a non aggressive environment, being raised by a non aggressive father, they were still aggressive suggesting it had been inherited (nature)

Question 13

What three things can be talked about in AO1 for genetic explanations?

Answer 13

-Twin studies
-Adoption studies
-Genes

Question 14

What is the main gene associated with aggression?

Answer 14

The MAOA Gene (Monoamine oxidase A)

Question 15

How was the MAOA gene linked to aggression?

Answer 15

Has been implicated in aggression as it was found that mice with the gene were extremely aggressive

Question 16

What does the MAOA gene do?

Answer 16

-It affects levels of neurotransmitters
-MAOA is an enzyme that breaks down NT in the brain, including serotonin (this is controlled by MAOA gene)

Question 17

Is the MAOA gene rare?

Answer 17

NO, this is a common misconception! We all have the MAOA gene though we may have different variants of this gene
-One example of a variant is MAOA-L variant: leads to reduced MAOA enzyme
-Other example is MAOA-H variant: leads to increased MAOA enzyme

Question 18

How do MAOA gene variants icnrease aggression?

Answer 18

Because it leads to an imbalance of serotonin, increasing aggression

Question 19

How is the MAOA-L variant said to icnrease aggression?

Answer 19

-By having less of the enzyme MAOA, it is not breaking down serotonin as much, leading to higher amounts of serotonin which has been shown to cause increased aggression

Question 20

Does high serotonin levels cause aggression or low levels of serotonin?

Answer 20

Arguably both do, so a better explanation would be that an “imbalance” in serotonin levels causes aggression

Question 21

what term must be used when referring to genetics?

Answer 21

Inheritance

Question 22

Twin, adoption studies and MAOA-L gene are not genetic factors, what are they?

Answer 22

They are simply evidence that genetics are a factor in aggression (DON’T FORGET THIS!)

Question 23

What are the evaluations of genetic explanations of aggresion?

Answer 23

😂Evidence to support (Cases et al)
😂Evidence to support (Brunner)
😢/😂Deterministic (no free will / cause and effect)
😢Reductionist

Question 24

What was found in the study Cases et al?

Answer 24

-Genetically engineered mice with MAOA-L, found these had atypical serotonin levels and behaviour
-Showing that there’s a genetic influence on aggression as having defective MAOA gene is found to increase levels of aggression

Question 25

What was found in study Brunner?

Answer 25

-Studied 28 male members of a large Dutch family repeatedly involved in aggressive violent crime such as rape, murder and assault
-Found these man had MAOA-L
-Adds to validity of genetic factors in aggression as men with defective MAOA-L gene increased levels of aggression
-Causing less of enzyme and therefore increased serotonin