Table 4.

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

Twin birth cohort	Nfamilies (%)	Grandfather		Grandmother		Spousal correlation
		Prevalence	95% CI	Prevalence	95% CI	Coefficient (μ)	95% CI
1940-	580	0.77	(0.73–0.80)	0.33	(0.29–0.37)	0.37	(0.22–0.50)
1932–1939	980	0.76	(0.73–0.78)	0.25	(0.22–0.28)	0.38	(0.26–0.49)
1924–1931	975	0.76	(0.73–0.78)	0.17	(0.15–0.20)	0.48	(0.43–0.59)
1916–1923	581	0.72	(0.68–0.75)	0.08	(0.06–0.11)	0.19	(−0.02–0.38)NS
pre 1915	239	0.64	(0.57–0.70)	0.06	(0.03–0.09)	0.47	(0.10–0.75)