bregdan 2005 twin study

Question 1

when was the study?

Answer 1

2005

Question 2

what awas the aim of the study?

Answer 2

compared to physical aggression to what extent social aggression was down to genetics, shared or non ahred environment

Question 3

what type of design was the study?

Answer 3

a ongoing longitudinal study

Question 4

where were the participnats from?

Answer 4

montreal cnanda

Question 5

what years did the participants have to be born between?

Answer 5

1995-1998

Question 6

how old were the participnats?

Answer 6

6 years old

Question 7

what wa sthe attrition rate per year?

Answer 7

2%

Question 8

how many twins were there in total?

Answer 8

234

Question 9

how many female mz twins was there?

Answer 9

50

Question 10

how many male mz twins were there?

Answer 10

44 94 mz

Question 11

how many female dz twins were there

Answer 11

32

Question 12

how many male dz twins were there?

Answer 12

41 73 dz

Question 13

how many mixed dz twins were there?

Answer 13

67

Question 14

when was the sample assessed?

Answer 14

5, 18, 30, 48 and 60 months

final data taken at 6 years

Question 15

how was written consent gained?

Answer 15

written from parents

Question 16

how many children were in the same class?

Answer 16

who rated the students and on what?

Question 17

who rated the students and on what?

Answer 17

teachers on social and physical aggression

Question 18

what did the teachers use to rate the students?

Answer 18

the preschool behaviour scale and direct and in direct aggression scale

Question 19

how else did they rate the students?

Answer 19

using a three point scale

0=never

Question 20

how was peer ratings conducted?

Answer 20

children were given a booklet of every classmates face they had to circle 3 students that best fit for descriptors
2 physical 2 social
nominators added up and turned into aggression scores

Question 21

who was found to be more physically aggressive?

Answer 21

boys

Question 22

what was found about physical aggression?

Answer 22

that mz scores were twice as high as dz for both teacher and peer ratings

Question 23

for social aggression what was found?

Answer 23

that mz and dz scores were similar showing that shared environment may explain S aggression

Question 24

what was the overall conclusion?

Answer 24

that 50-60% of physical aggression was due to heritable factors
environmental factors influence SA
high level of physical aggression lead to high S but not other way round

Question 25

what wa the overall correlation?

Answer 25

it was modest correlation (not strong)

Question 26

what does a modest correlation show?

Answer 26

that behaviour is not purely linked to genetics

non shared environment must play a part

Question 27

what percent of social aggression cam be explained by genes?

Answer 27

20%

Question 28

what percent of physical aggression can be explained by genes?

Answer 28

50-60%