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Brendgen (2005)- twin study - Coggle Diagram
Brendgen (2005)- twin study
aim
causes of physical and social aggression?
can one type of aggression lead to another?
genes or shared environment?
procedure
quebec newborn twin study, montreal, canada
123 twin pairs with varied zygosity, DNA tested, 94% agreement
234 twin pairs
84% european descent
materials in french and english, checked by bilingual judges
teacher and peer ratings. teacher ratings: 0/1/2 rate on the scale how much the statement links with child, 'spreads nasty rumours'. peer ratings: photo booklets, circle 3 that match description- 'tells mean secrets'
tested at 6 years in spring term- 409 classrooms, 45 min per class
results
physical aggression can lead to social but not opposite way around
physical aggression 2x higher in MZ than DZ in teacher and peer ratings
social aggression almost equal between MZ and DZ
conclusions
physical agg 50-60% due to genes
young children are capable of using complex manipulative strategies
social aggression better explained due to e'ment: 20% genes, 20% shared e'ment, 60% non shared e'ment
evaluation