Aggression - The Role of Genetic Factors

Question 1

Mason and Frick

Answer 1

meta-analysis of twin and adoption studies - found 50% genetic heritability estimate

Question 2

Coccaro

Answer 2

182 MZ twins 118 DZ twins - assessed degree of genetic and environmental influences on aggression - found more than 40% genetic

Question 3

Hutchings and Mednick

Answer 3

14,000 adoptions - significant positive correlation between number of criminal convictions for violence among biological parents and number of violence in sons

Question 4

Caspi

Answer 4

not everyone with defective MAOA gene becomes aggressive - a defective gene only causes a significant rise in aggression if it is paired with severe maltreatment at childhood

Question 5

Brunner

Answer 5

studied a family who had highly aggressive males - found they were all suffering from a defective MAOA gene and as a result high levels of neurotransmitters in their urine