Why Don’t Smart Teens Have Sex? A Behavioral Genetic Approach


  • Dr. Paige Harden is a Faculty Research Associate of the Population Research Center at the University of Texas at Austin, which is supported by a center grant from the National Institute of Child Health and Human Development (NICHD; Grant 5-R24-HD042849). The authors thank Dr. Elliot M. Tucker-Drob for helpful comments on earlier drafts of this manuscript. This research uses data from AddHealth, a program project designed by J. Richard Udry, Peter S. Bearman, and Kathleen Mullan Harris, and funded by a Grant P01-HD31921 from the Eunice Kennedy Shriver NICHD, with cooperative funding from 17 other agencies. Special acknowledgment is due Ronald R. Rindfuss and Barbara Entwisle for assistance in the original design. Persons interested in obtaining data files from AddHealth should contact AddHealth, Carolina Population Center, 123 W. Franklin Street, Chapel Hill, NC 27516-2524 (addhealth@unc.edu). No direct support was received from Grant P01-HD31921 for this analysis.

concerning this article should be addressed to Dr. Kathryn Paige Harden, 1 University Station A8000, Austin, TX 78712. Electronic mail may be sent to harden@psy.utexas.edu.


Academic achievement and cognitive ability have been shown to predict later age at first sexual intercourse. Using a sample of 536 same-sex twin pairs who were followed longitudinally from adolescence to early adulthood, this study tested whether relations between intelligence, academic achievement, and age at first sex were due to unmeasured genetic and environmental differences between families. Twins who differed in their intelligence or their academic achievement did not differ in their age at first sex. Rather, the association between intelligence and age at first sex could be attributed entirely to unmeasured environmental differences between families, whereas the association between academic achievement and age at first sex could be attributed entirely to genetic factors.