. Author manuscript; available in PMC: 2014 May 9.

Published in final edited form as: Behav Genet. 2013 Feb 10;43(3):208–219. doi: 10.1007/s10519-012-9581-7

Table 2.

Number of MZ and DZ twin pairs (N_MZ; N_DZ) within each age category for each study in the GHCA database

Study	Total N	Age 4–10	Age 11–13	Age 14–16	Age 17–34
Netherlands #1	125; 112	125; 112	0; 0	0; 0	0; 0
Netherlands #2	49; 63	49; 63	0; 0	0; 0	0; 0
Netherlands #3	79; 111	0; 0	79; 111	0; 0	0; 0
Netherlands #4	79; 108	0; 0	0; 0	13; 14	66; 94
Netherlands #5	36; 58	0; 0	0; 0	0; 0	36; 58
Netherlands #6	69; 69	0; 0	0; 0	0; 0	0; 0
Colorado #1	752; 1025	391; 534	204; 280	126; 173	31; 38
Colorado #2	215; 175	17; 6	13; 14	153; 125	32; 30
Colorado #3	332; 364	0; 0	30; 44	99; 140	203; 180
Minnesota #1	777; 469	43; 16	734; 453	0; 0	0; 0
Minnesota #2	410; 214	0; 0	0; 0	92; 31	318; 183
Australia	338; 515	0; 0	0; 0	324; 483	14; 32
Ohio	121; 171	121; 171	0; 0	0; 0	0; 0
UK	1529; 2532	394; 714	1135; 1818	0; 0	0; 0

Note. Samples used for the analysis of the individual studies are in boldface.