The causes of SPD are among the subjects that researchers at Sensory Processing Disorder Foundation and their collaborators elsewhere have been studying. Preliminary research suggests that SPD is often inherited. If so, the causes of SPD are coded into the child's genetic material. Prenatal and birth complications have also been implicated, and environmental factors may be involved.
Of course, as with any developmental and/or behavioral disorder, the causes of SPD are likely to be the result of factors that are both genetic and environmental. Only with more research will it be possible to identify the role of each. (From SPD Foundation's website)