Genetic factors in aggression Flashcards
What are the three ways used to see if genetic factors affect aggression?
Twin studies
Adoption Studies
The mama gene
Who conducted twin studies to see if being twins affected aggression? (thus genetics)
Corraco 97 twin studies
What was Corraco 97 twin studies on aggression?
Used a self-report questionnaire to measure hostility in 182 MZ and 118 DZ twin pairs.
What was the findings of Corraco 97 twin studies on aggression?
He concluded that genes contributed 47% to direct assault, 37% to irritability and 28% to verbal assault.
As concordance rates were not 100%, environmental influences must play a role.
Who conducted a adoption study to see if genetic factors cause contribute towards aggression?
Hutchings 75
Hutchings 75 adoption study procedure?
Studied over 14,000 adoptions in Denmark.
Hutchings 75 adoption study findings
Where neither biological nor adoptive father had a criminal record, the son received a criminal record 10% of the time.
This rose to 11% where the adoptive father had a criminal record, 21% where the biological father had one, and 36% where both adoptive and biological father had a criminal record.
Hutchings 75 adoption study conclusions
Although this strongly suggests a genetic link, the study measured whether songs received criminal records and only a small proportion of crime involves direction aggression.
What protein has been associated with aggression?
Although no individual gene for aggression has been identified in humans, a gene responsible for producing a protein called MAOA has been associated with aggression.
What is the MAOA gene?
Regulates the metabolism of serotonin in the brain, and low levels of serotonin are associated with impulsive, aggressive behaviour.
What evidence suggests that the MAOA gene is associated with aggression?
Brunner 93 studied a Dutch family where many males members behaved aggressively and had been involved in violent crime. They were found o have abnormally low levels of MAOA and a defect in the gene responsible for producing MAOA.
Caspi 02 study MAOA indicates interaction between genes and the environment in determining aggression.
What evidence is there against the 3 supporting studies suggesting that aggression is determined by genetic factors?
Studies have often focused on criminal behaviour rather than actual aggression, and on twins and adopted children. Research has not focused on more low-level non-criminal aggression normal members of the population are likely to engage in. Also, even violent criminals may have only been violent once. Thus, extraneous variables and population validity are issues in most genetic studies of aggression.
There are numerous difficulties in deterring exactly what influence genes have on aggression. More than one gene probably contributes to aggression, a variety of environmental influences have the potential to affect aggression and separating out the effect of genetic inheritability from environmental influences is difficult.
Different studies have operationalised aggression in different ways and these may all have problems with validity. For example, self-ratings and peer ratings are subjective and biased by personal interpretation and the respondent providing socially appropriate answers.
