Genetic factors

Question 1

Is biology an important indicator in agression

Answer 1

• yes!
• high levels of testosterone and fluctuating levels of serotonin could be genetically determined
• this could suggest that certain individuals/families could display higher levels of agressive behaviour because of their predisposition to biochemical differences from the majority of the population

Question 2

Twin studies- Coccaro et al (1997)

Answer 2

• studies adult male MZ and DZ twins
• aggression was operationalised as direct physical assault
• researchers found concordance rates of 50% for MZ twins and 19% for DZ twins
• for verbal agression, concordance figures were 28% for MZ twins and 7% for DZ
• because MZ twins share same gene, agression is higher

Question 3

Adoption studies- Soo Rhee and Waldman (2002)

Answer 3

• carried out meta analysis of adoption studies of direct agression and ASB
• found that genetic influences accounted for 41% of the variance in agression, more of less in line with the findings from twin studies
• suggests there is a genetic influence operating in agressive behaviour

Question 4

What is the MAOA gene and what is it’s role in aggression

Answer 4

• it is an enzyme and ‘mops up’ NTs in the brain after a nerve impulse has been transmitted from one neuron to another
• a dsyfunction in the operation of this gene will lead to abnormal activity of the MAOA enzyme, which will increase levels of serotonin in the brain
• an allele of the MAOA gene leads to low MAOA activity in areas of the brain and has been associated with agressive behaviour
• low MAOA= aggression

Question 5

Brunner at al (1993)- MAOA research

Answer 5

• studies 28 male members of a large Dutch family who were involved in impulsively agressive violent criminal behaviour
• researchers found that these men had abnormally low levels of MAOA in their brains and the low activity version of the MAOA gene
• this means there were higher levels of noradrenaline and dompamine
• however this research has legal implications, as the men could claim they are victims of their own genes

Question 6

McDermott et al (2009)- research for MAOA

Answer 6

• pps with low activity MAOA gene behaved aggressively in a lab based money allocation game, but only when provoked
• otherwise they were no more/less agressive than other pps
• suggests low MAOA doesn’t cause agression

Question 7

How does the MAOA gene link to early traumatic events

Answer 7

• genes are crucial influences on aggressive behaviour but they do not function in isolation
• low MAOA gene activity is only related to adult agression when comvined with early traumatic life events

Question 8

Frazzetto et al (2007)- MAOA gene link to early traumatic events

Answer 8

• found an association between higher levels of AS aggression and the low activity MAOA gene allele in adult males
• this was only the ccase in those who had experienced significant trauma during the first 15 years of life
• those who had not experienced trauma in their childhood did not have high levels of agression as adults, even when they possessed the MAOA low activity allele

Question 9

Research to back up Frazzetto- Moffitt et al (1992)

Answer 9

• 442 NZ males studied from birth to age 26
• a record was kept of abuse experienced and the presence of the low activity MAOA gene
• found that those who had suffered abuse and had the low activity version of the gene were 9x more likely to indulge in anti social behaviour

Question 10

Evaluation- one gene involved?- Vasos et al (2014)

Answer 10

• found no association between any single gene and aggression
• their explanation for this is that even serveral genes are unlikely to fully explain a behaviour as multifaced aggression
• the researchers calculate that hundreds or thousands of genes interact in a complex way to determine agressive behaviour, casting doubt over any research for single candidate genes
• suggests that a combination of genes interact and explanation is reductionist as only looking at one gene for behaviour

Question 11

Evaluation- other factors

Answer 11

• cannot separate nature and nurture- someone may have low activity of MAOA gene but not be agressive- or agressive behaviour may be done to environment
• social and environmental factors ignored