Table A2

Summary Statistics—Families with and without Twins

	2+ Sample				3+ Sample
	No Twins		With Twins		No Twins		With Twins
	Mean	Standard Deviation	Mean	Standard Deviation	Mean	Standard Deviation	Mean	Standard Deviation
Panel A: 10–15-years-old
Father’s age	38.68	6.17	38.75	6.47	38.78	6.05	39.16	6.83
Mother’s age	34.63	4.89	34.81	5.13	34.47	4.62	34.45	4.79
Father’s education	5.36	4.39	4.70	4.23	4.58	4.16	3.77	3.89
Mother’s education	5.43	4.09	4.70	3.96	4.69	3.88	3.92	3.61
Child age	12.34	1.70	12.40	1.69	12.11	1.62	12.18	1.61
White child	0.61	0.49	0.54	0.50	0.54	0.50	0.45	0.50
Urban area	0.74	0.44	0.68	0.47	0.68	0.47	0.61	0.49
Metro area	0.27	0.44	0.25	0.44	0.23	0.42	0.18	0.39
Panel B: 18–20-years-old
Father’s age	45.62	6.13	45.77	6.29	45.40	5.95	45.27	5.68
Mother’s age	41.42	4.78	41.71	5.12	41.03	4.47	40.73	4.76
Father’s education	5.03	4.39	4.23	4.29	4.50	4.19	3.95	4.00
Mother’s education	4.82	4.01	4.05	4.01	4.34	3.83	3.72	3.79
Young adult age	18.87	0.81	18.90	0.81	18.76	0.79	18.71	0.78
White young adult	0.64	0.48	0.56	0.50	0.59	0.49	0.51	0.50
Urban area	0.76	0.43	0.68	0.47	0.72	0.45	0.67	0.47
Metro area	0.31	0.46	0.27	0.45	0.28	0.45	0.24	0.43