early psychologists believed cause of aggression lies in the Y chromosome. genotype XYY "supermales". selective breeding shows aggression is a gene that can be transmitted
Court- Brown (1965)?
314 patients has XXY and put forward the view they should remain hospitalised.
twins?
higher concordance rate in MZ twins than DZ means aggression has a genetic element.
MAOA gene?
dysfunction in gene can lead to noradrenaline, adrenaline and dopamine not being broken down. If adrenaline not broken down then can cause a hypersensitive fight-or flight
Dopamine?
high- increases feeling of reward from aggressive behavior
Serotonin?
low- lack of inhibition over impulsive behaviours.
Noradrenaline?
high- overreaction to perceived threats
Theilgaard (1984)?
men with XYY genotype and found XYY can increase in height with individuals but not aggression
Coccaro et al (1997)?
compared MZ vs DZ twin. MZ twins 50% concordance rate vs DZ twins 19%
Godar et al (2014)?
selective breeding, removing knock out gene in mice. MAOA knockout showed increased aggression, higher levels of serotonin. serotonin levels normal: behaviour stabilised
Brunner (1993)?
study on an aggressive family. 5 of the males had dysfunctional MAOA gene. females unaffected. (Y chromosome)
Tuart et al (2014)?
97 men involved with severe domestic abuse. most violent men had faulty MAOA gene. men engaged in the highest level of physical and psychological aggression.
