7) Saudino, K.J., & Cherny, S.S. (2001). Sources of Continuity and Change in Observed Temperament. In R. Emde & J. Hewitt (Eds.), Infancy to Early Childhood: Genetic and Environmental Influences on Developmental Change (pp 89-110). Oxford University Press: New York, New York.

In this study, researchers analyzed measures of shyness, behavioral inhibition, and the Infant Behavior Record to examine continuity and change in observed temperament. They found that individuals in this sample demonstrated significant heritability of tester rated temperament across 14,20,24, and 36 months of age. Overall, there was no consistent pattern in the magnitude of genetic influence across age, and heritability did not appear to change dramatically during the transition from infancy to early childhood.