Twin studies aggression

• Some people may be aggressive due to genetic inheritance; Researchers compare concordance rates for traits such as aggression between MZ and DZ twins
• Coccaro study of the genetic transmission of aggression rather than general anti-social behaviour
• Coccaro- for physical assault concordance rate of 50% for MZ and 19% for DZ
• As MZ twins who share 100 percent of genes are more likely to share aggressive behaviour than DZ twins who share 50% of genes suggest that there is a genetic basis for aggression