Table 3

Results of the OLS (First Stage) Regressions Explaining Smoking in ALSPAC

	#Cigarettes Smoked per Day		#Cigarettes Smoked per Day (Adjusted)
	(1)	(2)	(3)	(4)
rs1051730	0.5**	0.4**	0.6**	0.6**
rs1051730	(0.1)	(0.1)	(0.2)	(0.1)
Control variables	No	Yes	No	Yes
R-squared	0.004	0.132	0.005	0.202
Effective F-statistic	25.3	27.2	15.6	15.1
N	7,598	7,598	3,784	3,784

Notes: Coefficients are displayed with robust standard errors in parentheses. Column 1–2 use the self-reported smoking measure, and Column 3–4 the self-reported smoking measure corrected using cotinine levels. All regressions correct for genetic relatedness among the mothers using the first four principal components of the genetic relationship matrix. +p < 0.1, *p < 0.05, **p < 0.01.