genetic explanations for aggression Flashcards
(6 cards)
what do genetic explanations of aggressions suggest?
genetic explanations suggests that aggressive behaviours are inherited and the genes are passed on from family members the more genetiaclly relate individuals are the more likely they are for developing the aggressive tendencies
how can we study genetics
family studies ( the closer the biological relationship the higher the concordance rate)
adoption studies (aim to control for the separation of nuture and nature)
twin studies
twin studies supporting evidence
- Cocaro (1997) compared mz and dz male vietnamese twins, finding the genetic difference did account for differences in aggression eg 47% of direct assault
problems with identical twin research is they might have social pressure to make the act more alike , more similar experiences which could account for the higher concordance rate of aggression
adoption study supporting evidence
- criminality is often associated with aggression
Mednick and Hutchings (1978)
found 10.5% of Danish adoptees with non criminal biological fathers were criminals compared to 21.4% with criminal biological fathers
early genetic (gene candidates) for aggression
the idea of the XYY (chromosomal disorder)
early theories suggested that these were super males either ‘taller, genetically more aggressive and low in empathy and over represensative in prison systems
However the early research was flawed XXY males were not over repersenative in prison systems as suggested and although were taller and stronger they were not more aggressive this theory is now completely rejected
- MAOA is an enzyme that breaks down the neurotransmitter Serotonin the low activity variant MAOA - L is associated with aggression
this is because it results in low production of the MAOA enzyme leading to higher levels of serotonin the brain - too much serotonin causes an imbalance in the how the brain process and regulates emotion
this low activity variant is also known as the warrior gene and is found in 1/3 of men and over 60% of some communities however not all these men are aggressive - it is therefore the combination of the MAOA- L gene (leading to high serotonin levels and other factors such a stress, early trauma ) a vulnerability is needed to trigger this gene (diathesis stress model of aggressive behaviour
general evaluations for aggressive behaviour
- Brunner (1993) conducted a case on an extended family in the Netherlands
the males had a history of impulsive aggression and attempted rape. Males in the family had low activity of MAOA genes. This suggests extreme levels of aggression can have a genetic origin that leads to neurological abnormality
Stutart et al (2014) researched 97 men who had committed intimate partner violence a genetic analysis revealed he defective MAOA hene was present in most of the physically and psychologially aggressive offenders which suugests the MAOA - L has a role to play in the expression of aggressive behaviour
The MAOA - L hypotheiss shows a correlation between high levels of aggression and high levels of serotonin . The mechanism of how this results is not completely understood - condracting the serotonin deficeny hypothesis - going against theories which suggest that low levels of serotonin are linked to aggressive behaviours. THis suggests the role of serotonin is complex , it is not simply high levels or low levels but how sensitive the brains serotonin receptors are
1/3 of the western men have a MAOA L and twin studies and adoption studies do not account for 100% of the variance in aggression therefore illustrating that genetic theories are not a full explanation of aggression there must be a social factor
