Table 2.

Interclass and intraclass correlations in different pairs of relatives for smoking initiation, persistence, and quantity.

Type of Relatives	Initiation Correlation (s.e.)	Persistence Correlation (s.e.)	Quantity Correlation (s.e.)
parent:offspring	0.09 (0.04)*	0.18 (0.07)*	0.16 (0.07)*
sibling	0.20 (0.04)***	0.07 (0.05)	0.12 (0.06)
half-sibling	-0.56 (0.25)	---	-0.55 (0.39)
grandparent	0.06 (0.08)	0.18 (0.17)	-0.08 (0.22)
avuncular	0.01 (0.04)	0.02 (0.05)	0.05 (0.06)
half-avuncular	-0.24 (0.28)	---	---
cousin	0.07 (0.04)	0.04 (0.05)	0.11 (0.07)
mother:father	0.24 (0.08)**	0.23 (0.11)*	-0.003 (0.123)

s.e.: standard error; * p ≤ 0.05 ** p ≤ 00; *** p ≤ 001.