Infant viewing of social scenes is under genetic control and is atypical in autism

Monozygotic twins show high concordance in eye- and mouth-looking, and this behaviour is markedly reduced in toddlers with autism spectrum disorder. An infant's view of the social scene An early and critical aspect of infant development is visual exploration of socially relevant stimuli such as faces and biological motion. Warren Jones and colleagues present an eye-tracking study of both typically developing children and those with autism to show that several aspects of visual social engagement, including propensity to look at facial features, as well as spatial and temporal dynamics of gaze, are highly heritable. Some measures of social visual engagement that are most highly heritable, such as attention to faces, are also those that most clearly distinguish typically developing children from those with autism. The authors propose social visual engagement as a neurodevelopmental endophenotype that is not just relevant for autism, but also broader population-wide variation. Long before infants reach, crawl or walk, they explore the world by looking: they look to learn and to engage 1 , giving preferential attention to social stimuli, including faces 2 , face-like stimuli 3 and biological motion 4 . This capacity—social visual engagement—shapes typical infant development from birth 5 and is pathognomonically impaired in children affected by autism 6 . Here we show that variation in viewing of social scenes, including levels of preferential attention and the timing, direction and targeting of individual eye movements, is strongly influenced by genetic factors, with effects directly traceable to the active seeking of social information 7 . In a series of eye-tracking experiments conducted with 338 toddlers, including 166 epidemiologically ascertained twins (enrolled by representative sampling from the general population), 88 non-twins with autism and 84 singleton controls, we find high monozygotic twin–twin concordance (0.91) and relatively low dizygotic concordance (0.35). Moreover, the characteristics that are the most highly heritable, preferential attention to eye and mouth regions of the face, are also those that are differentially decreased in children with autism ( χ 2 = 64.03, P