Table 1

Estimates from twin studies of genetic (A), shared environmental (C), and non-shared environmental (E) influences on smoking initiation and persistence in women and men

	Women			Men
	A	C	E	A	C	E
Initiation
Sweden⁹	44	42	14	51	39	10
Denmark¹⁰	79	–	21	84	–	16
Finland¹¹	37	50	13	50	33	17
Australia¹²	77	4	19	28	43	29
Australia¹³	60	26	14	80	–	20
USA second world war veterans¹⁴	–	–	–	59	21	20
USA Virginia¹²	84	–	16	84	–	16
USA Vietnam veterans¹⁵	–	–	–	39	49	12
Persistence
Sweden⁹	59	–	41	52	–	48
Finland¹⁶	71	–	29	68	–	32
Australia¹⁷	53	–	47	53	–	47
Australia¹³	62	–	38	62	–	38
USA⁸	58	–	42	58	–	42
USA Vietnam veterans¹⁵	–	–	–	69	–	31