Table 3.

Prevalence and spousal correlation of lifetime smoking for the parental generation, as a function of twin birth cohort

Twin birth cohort	Nfamilies (%)	Father		Mother		Spousal correlation
		Prevalence	95% CI	Prevalence	95% CI	Coefficient(μ)	95% CI
1964–1971	2181	0.68	(0.66–0.70)	0.42	(0.42–0.44)	0.41	(0.37–0.41)
1956–1963	1046	0.68	(0.68–0.70)	0.34	(0.31–0.37)	0.46	(0.45–0.46)
1948–1955	838	0.71	(0.71–0.71)	0.35	(0.34–0.35)	0.45	(0.45–0.47)
1940–1947	532	0.71	(0.68–0.74)	0.32	(0.32–0.33)	0.39	(0.38–0.42)
1932–1939	285	0.76	(0.71–0.79)	0.26	(0.24–0.27)	0.27	(0.24–0.33)
1924–1931	258	0.75	(0.71–0.77)	0.18	(0.18–0.23)	0.19	(−0.05–0.42)NS
pre 1923	213	0.62	(0.61–0.69)	0.09	(0.05–0.11)	0.34	(0.10–0.53)

The path coefficients of offspring report on parental history of smoking were in the range of 0.952–0.993 for fathers and 0.965–0.997 for mothers.