Abstract
To what extent do individual differences in infants’ early preference for faces versus non-facial objects reflect genetic and environmental factors? In a sample of 536 5-month-old same-sex twins, we assessed attention to faces using eye-tracking in two ways: initial orienting to faces at the start of the trial (thought to reflect subcortical processing) and sustained face preference throughout the trial (thought to reflect emerging attention control). We show that both face orienting and preference were heritable (h² = .19, CI: .04-.33; h² = .46, CI: .33-.57, respectively); while shared environment was statistically nonsignificant.
Face preference was associated positively with later parent-reported verbal competence (β = 0.14, p = .014). This is the first study to show that individual differences in young infants’ selection of perceptual input – social versus non-social – are heritable, providing a new developmental perspective on gene-environment interplay occurring at the level of eye movements.