Twin cohort associated_with aggression

The twin correlations ... can be used to estimate the genetic and environmental influences to aggressive behavior.

Evidence of G × E interaction in aggressive behavior has been reported in twin ... studies

Findings ... show no differences in mean levels between MZ and DZ twins in ... proactive aggression.

twins and singletons have been found to display similar scores on aggressive behavior

raters are less able to discriminate between the two twins' aggressive behavior and thus inflate the similarities between them, regardless of zygosity

Studies ... including both twin ... samples show that about half of the variance in aggressive behavior is explained by genetic influences.