One train of thought is that autism is a combination of genetic differences in several genes affected by some form of environmental influence that causes the individual to suffer the autistic traits. It is also been a source of interest in that most autistic people have been diagnosed with at least one other primary or secondary illness most often notably mental illnesses such as bi-polar or hyperactivity.
For many years autism was thought of as a disease caused by a lack of nurturing in the individual's life as an infant. It was felt that the lack of a Telephone Number List loving environment would cause the introspective symptoms that so often accompany the severe phases of autism so a genetic explanation was not researched early on in the discovery of the illness.
However, most recent studies have taken the time to study the evidence provided by autistic individuals and the conclusion seems to point the direction towards a definite link to a genetic cause. One of the most prevalent pieces of evidence that shows there is a connection between autism and genetics is the fact that twins always display the same autistic tendencies. A set of twins not sharing the autistic symptoms has yet to be found among the many research models from autism.