Genetic factors involved in aggression

Question 1

Twin studies - adult twins

Answer 1

nearly 50% of variance in direct aggressive behaviour attributed to genetic factors

Question 2

Adoption studies - Denmark

Answer 2

14,000 adoptions, significant number of boys with criminal convictions had biological parents with criminal convictions

Question 3

What does MAOA do?

Answer 3

regulates metabolism of serotonin in the brain

low levels of serotonin associated with aggression

Question 4

Genes - Dutch family

Answer 4

1980s, many M members behaved violently
large no. involved in violent crimes
abnormally low lev. of MAOA, defect later identified

Question 5

Gene-environment interaction - Caspi et al

Answer 5

500 M children, variant assoc. with high/low lev. of MAOA

low lev. + maltreated, more likely to exhibit antisocial behaviour

Question 6

Genetics and violent crime

Answer 6

inherited temperament place some more at risk of committing violent crime

Question 7

Meta-analysis - Miles and Carey

Answer 7

24 twins and adoption studies, results suggested strong genetic influence that could account for 50% of variance
genes and family environment influential in determining aggression in youth, later - genes more

Question 8

Rhee and Waldman

Answer 8

51 twins and adoption studies

aggressive behaviour largely product of genetic contributions

Question 9

Miles and Carey - problems

Answer 9

mode of assessment sig. moderator
genetics explained variance in studies that used parent/ self-report
observational ratings, more environment

Question 10

Inconclusive evidence - meta-analysis, youth crime

Answer 10

meta-analysis found low/moderate correlation between heredity and crime
better designed, more recent, less support
recent review of youth crime studies, do not suggest strong role of heredity

Question 11

Inconclusive evidence - meta-analysis, youth crime

Answer 11

meta-analysis found low/moderate correlation between heredity and crime (Walters)
better designed, more recent, less support
recent review of youth crime studies, do not suggest strong role of heredity

Question 12

Value of animal research

Answer 12

rodents, experimental manipulations, test effects of specific genes, selective breeding programmes
Young et al: genetic mutation (‘fierce’) that causes violent behaviour in mice
counterpart identified in humans, precise functions unknown