Children with autism spectrum disorder (ASD) or with Down syndrome (DS) show diagnosis-specific differences from typically developing (TD) children in gesture production. We asked whether these differences reflect the differences in parental gesture input. Our systematic observations of 23 children with ASD and 23 with DS (M[subscript ages] = 2;6)--compared to 23 TD children (M[subscript age] = 1;6) similar in expressive vocabulary--showed that across groups children and parents produced similar "types" of gestures and gesture-speech combinations. However, only children--but "not" their parents--showed diagnosis-specific variability in how often they produced each type of gesture and gesture-speech combination. These findings suggest that, even though parents model gestures similarly, the amount with which children produce each type largely reflects diagnosis-specific abilities.