TY - JOUR A1 - Kohler, H.P. A1 - Rodgers, J.L. A1 - Christensen, K. T1 - Is fertility behaviour in our genes? Findings from a Danish twin study Y1 - 1999 DO - 10.1111/j.1728-4457.1999.00253.x JF - Population and Development Review VL - 25 SP - 253 EP - -288 ER -