Table 3.

Population characteristics of individual twins, surviving to age 6, birth cohorts 1961–1990.

	All Subjects 1961–1990	Males 1961–1990	Females 1961–1990
Total, n (pairs)	39,504 (20,232)	19,964 (13,266)	19,540 (13,000)
Age at FU a, mean (SD)	40.3 (9.6)	40.2 (9.5)	40.5 (9.6)
Sex, n (%)
Male	19,964 (50.5)	19,964 (100.0)	-
Female	19,540 (49.5)	-	19,540 (100.0)
Zygosity, n (%)
MZ	9906 (25.1)	4689 (23.5)	5217 (26.7)
SSDZ	12,103 (30.6)	6159 (30.9)	5944 (30.4)
OSDZ	12,317 (31.2)	6143 (30.8)	6174 (31.6)
UZ	5178 (13.1)	2973 (14.9)	2205 (11.3)
Dead during FU a, n (%)
No	38,519 (97.5)	19,334 (96.8)	19,185 (98.2)
Yes	985 (2.5)	630 (3.2)	355 (1.8)

^a FU is defined as time until death, censoring (emigration) or end of study period (1 October 2016).