Using the Flanker Task to Examine Genetic and Environmental Contributions in Inhibitory Control Across the Preschool Period.

The limited research exploring genetic and environmental influences on inhibitory control (IC) in preschoolers has relied on parent ratings or simple delay tasks and has produced mixed results. The present study uses a cognitively-challenging Flanker task to examine genetic and environmental contributions to the development of early IC in a longitudinal sample of 310 same-sex twin pairs (123 MZ; 187 DZ; 51% female) assessed at ages 3, 4 and 5 years. IC was significantly heritable at each age (a 2 : age 3 = .36; age 4 = .36; age 5 = .35). Stability was entirely accounted for by genetic influences, and change was explained by genetic and nonshared environmental factors. No significant shared environmental influences were observed.