Brendegen - Results

Question 1

GENETIC LINK: Concordance rates for physical aggression

Answer 1

MZ concordance rates were nearly twice as high as same-sex DZ concordance rates for physical aggression in both teacher and peer ratings. This suggests that physical aggression is most likely genetically caused

Question 2

GENETIC LINK: Concordance rates for social aggression

Answer 2

MZ concordance rates and same-sex DZ concordance rates for social aggression were similar in both teacher and peer ratings. This suggests that social aggression is most likely environmentally caused

Question 3

GENETIC LINK: Size of these correlations

Answer 3

For both MZ and DZ twins, the size of these correlations was only moderate, suggesting a high contribution in both types of twins for non-shared environment

Question 4

GENETIC, SHARED, or NON-SHARED: Teacher ratings of physical aggression

Answer 4

According to teacher ratings for physical aggression, 63% of the time this appeared to be caused by genetics and 37% of the time by non-shared environment

Question 5

GENETIC, SHARED, or NON-SHARED: Teacher ratings of social aggression

Answer 5

According to teacher ratings of social aggression, 20% of the time this appeared to be caused by genetics, 20% of the time by shared environment, and 60% of the time due to a non-shared environment

Question 6

GENETIC, SHARED, or NON-SHARED: Peer ratings of physical aggression

Answer 6

According to peer ratings of physical aggression, this was genetically caused 54% of the time and by non-shared environment 46% of the time

Question 6

GENETIC, SHARED, or NON-SHARED: Peer ratings of social aggression

Answer 6

According to peer ratings of social aggression, this was genetic 23% of the time, caused by shared environment 23% of the time, and caused by non-shared environment 54% of the time