I'm not sure that I'm totally clear on what your question is here, but know a little bit about Sensory Integration Dysfunction and would be happy to talk to you about it.
In the meantime, a good website for info about this disorder is: http://www.kid-power.org/sid.html
Let me know how I can help.
There is not enough research on this disorder to answer this question conclusively, but most studies suggest that there is a biological component to it. As you probably know, sensory intergration dysfunction is related to Autism, Asberger's Syndrome, and ADD- all of which have hereditary components.
As this disorder is more widely recognized and more is learned about it there will probably be more research on what causes it, but right now no one really knows for sure how much is hereditary and how much is environmental.