**Abstract**

During 1950 to 1975 autism was considered to be psychopathological in origin, brought on by 'bad' mothering in particular. Subsequently, research into the etiology of autism spectrum disorder (ASD) has been dominated by the neurodevelopmental paradigm according to which ASD is genetic or biological in origin. In the present paper population cohort data for Israel are used to show that recurrence risk of ASD (when more than one child has ASD) depends on three parent-related phenomena. First, it varies inversely with the 'veil of ignorance' defined as the period of time younger siblings were raised before their elder sibling was diagnosed. Second, it varies inversely with the 'shadow of ASD' defined as the period during which parents raised their child with ASD before younger siblings were born. Third, recurrence risk is greater if parents knew the ASD status of their child before conceiving their next child. These three effects, which are shown to be consistent with a behavioral theory of ASD, are inconsistent with neurodevelopmental theory. They suggest that what parents know or do not know about the ASD status of their child is salient for recurrence risk in their subsequent children.

**Keywords:** reproductive stoppage, natural experiment, recurrence risk, psychopathology of ASD, neurodevelopmental theory, population cohort data, diagnostic timing
