11) Zahn-Waxler, C., Schiro, K., Robinson, J.L., Emde, R.N., Schmitz, S. (2001). Empathy & Prosocial patterns in young MZ & DZ Twins: Development and Genetic and Environmental Influences. In R. Emde & J. Hewitt (Eds.), Infancy to Early Childhood: Genetic and Environmental Influences on Developmental Change (pp 141-162). Oxford University Press: New York, New York.

This chapter focuses on empathic development in the second and third years of life. Twins were visited at home at ages 14, 20, 24 and 36 months by 2 female examiners. One to Three weeks later the twin pair visited the laboratory with their mothers. During these visits the twins’ responses to simulated distress were measured. Researchers found that as the twins aged, they exhibited increased empathy, and that girls scored higher on several empathic measures. They also found that MZ twins displayed more similar empathic responses than did DZ twins, indicating a genetic influence on empathy.