Table 1.

Concordance rates for schizophrenia in monozygotic twins and dizygotic twins.

	Monozygotic		Dizygotic
Authors	Total Number of Twin Pairs	Pairwise Concordance Rate (%)	Total Number of Twin Pairs	Pairwise Concordance Rate (%)
Luxenberger, 1928 [48]	19	58	13	0
Rosanoff et al., 1934 [49]	41	61	53	13
Kallman, 1953 [50]	174	69	296	11
Slater and Shields, 1953 [51]	37	65	58	14
Inouye, 1963 [52]	58	59	20	15
Tienari, 1963 [53]	17	35	20	13
Kringlen, 1967 [54]	55	45	90	15
Fischer et al., 1969 [55]	25	36	45	17
Essen-Möller, 1970 [56]	11	64	27	15
Gottesman and Shields, 1972 [39]	22	58	33	12
Fischer, 1973 [57]	21	56	41	27
Kendler and Robinette, 1983 [58]	164	31	268	7
Onstad et al., 1991 [59]	24	48	28	4
Franzek and Beckmann, 1998 [60]	9	67	12	17