Aggression – genetic factors Flashcards
What are the main way genetics for aggression can be examined?
Twin studies and adoption studies.
How are twin studies carried out?
Identical twins are compared between non-identical twins for level of aggression between them. This is because identical twins share the exact same make up as each other while non-identical share up to 50%. If I identical twins have more similar levels of aggression than it is thought to be due to genetics.
What did MacGuffin find?
When studying set of identical and non-identical twins; identical twins aggression levels correlated more highly at 87% compared to non-identical twins correlated at 72%. first glance appeared to support the basis of genetics being behind such similarities as aggression is shared more closely with twins with identical genetic suggesting shared genes may be responsible.
What is the genetic explanation of aggression?
Aggression is inherited.
What was Coccaros study into twins?
Compared MZ and DZ male Vietnamese twins, finding the genetic difference did account for differences in aggression, e.g 47% of direct assault.
How are twin studies used in the genetic explanation?
The higher the concordance rate the more genetic it is.
How are family studies used in genetic explanation for aggression?
The higher the concordance rate of aggression the more likely to be caused by the gene however it is difficult to control nurture.
What did Mednick and Hutchins find?
10.5% of danish adoptees with non criminal biological fathers were criminals compared to 21.4% of those with criminal biological fathers.
What is testosterone?
Produced in the testes. Normal gland development is affected by genetic makeup. This could be responsible for high levels for resulting in aggression.
What is the XYY chromosomal disorder?
It only affects males and they have an additional Y chromosome.
What is the MAOA-L gene?
MAOA is an enzyme that breaks down the neurotransmitter serotonin. The low activity variant is associated with aggression. It results in low production of MAOA enzyme leading to higher levels of serotonin in the brain.
What is meant by ‘the warrior gene’?
The low activity variant MAOA-L was nicknamed the warrior gene. Is found in one third of western men and over 60% of some communities. Not, all these men are aggression. Aggression only occurred if the men had a history of chid abuse. This is a Diathesis stress model of aggression.
