Infants' attention to eyes is an independent, heritable trait predicting later verbal competence

From birth, infants orient preferentially to faces, and when looking at the face, they attend primarily to eyes and mouth - two areas that convey different types of information. Here, in a sample of 535 5-month-old infant twins, we assessed eye (relative to mouth) preference in early infancy. Eye preference was independent from all other concurrent traits measured, and had a moderate-to-high contribution from genetic influences (A = .57; 95% CI: .45, .66). Preference for eyes over mouth at 5 months predicted higher parent ratings of verbal competence in toddlerhood, but did not predict autistic traits. These results suggest that variation in eye looking reflects a type of biological niche picking emerging before infants can select their environments by other means (crawling or walking).