Table 13

OLS Regression of Twin 2nd on Parental Education

Observed Family Background	Dependent Variable: Twin2nd
	Firstborn Female		Firstborn Male
	(1)	(2)	(3)	(4)
Panel A: Full Sample
Sample mean	0.0070	0.0070	0.0064	0.0064
Mother’s highest qualification
College degree+	0.0019^*	0.0020	0.0006	0.0003
Professional degree	0.0013	0.0014	−0.0001	−0.0006
High school diploma	0.0003	0.0004	0.0009	0.0004
Vocational high school diploma	0.0009^*	0.0009^*	−0.0001	−0.0005
Junior high school diploma	0.0006	0.0006	0.0001	−0.0001
Father’s highest qualification
College degree+		−0.0001		0.0006
Professional degree		−0.0001		0.0016^*
High school diploma		0.0002		0.0008
Vocational high school diploma		−0.0002		0.0010^*
Junior high school diploma		0.0004		0.0007^*
Sample size	416,315	416,315	434,729	434,729
Adjusted R-square	0.00015	0.00014	0.00010	0.00012
Panel B: First Two Births Before 1985
Sample mean	0.0065	0.0065	0.0059	0.0059
Mother’s highest qualification
College degree+	0.0024	0.0020	0.0004	0.0010
Professional degree	0.0013	0.0010	0.0007	0.0005
High school diploma	0.0007	0.0006	0.0015^*	0.0013
Vocational high school diploma	0.0009	0.0008	0.0001	−0.0002
Junior high school diploma	0.0001	0.0001	0.0004	0.0002
Father’s highest qualification
College degree+		0.0006		−0.0011
Professional degree		0.0005		0.0015^*
High school diploma		−0.0002		0.0007
Vocational high school diploma		−0.0003		0.0009^*
Junior high school diploma		0.0003		0.0004
Sample size	276,151	276,151	287,144	287,144
Adjusted R-square	0.00016	0.00015	0.00022	0.00025

Notes: This table reports the OLS estimated coefficient of demographic covariates in the regression D or Twin2nd by firstborn gender, conditional on the full set of indicators for urban, the firstborn’s age and district of birthplace, parents’ years of birth, and maternal age at the first birth.
↵* indicates significance at the 5% level.