The incidence of autism is increasing in both the USA and in Britain. There is still controversy over what causes autism and even greater controversy over selecting a preferred method of intervention and support (as there is no treatment for autism). Although there is now a general consensus that individuals may have a genetic predisposition to develop autism, it is also acknowledged that this may be off set by a range of environmental and/or biological factors. The understanding of the causation of autism is now considered in much the same way as we understand cerebral palsy, in that there can be a range of different reasons for causation and prevalence. This article, the first of two parts, will explore how an awareness and understanding ...