My notion was not one of existence, it was one of free will.
When a child or an adult participates in patently asocial behavior, and one subsequently can describe that clearly to be the consequence of a genetic malady, do I blame them?
It is not about existing, it is about the morality of judgement.
It is here:
http://www.ncbi.nlm.nih.gov/pubmed/21658581
(This is a stunning finding published in a "daughter of 'Cell' journal" ... 'Neuron', Cell Press being considered the most noteworthy and highest profile journals for matters of fundamental biology)
Duplicate the region get autism, delete the region and get a hyper-social disorder called Williams-Beuren syndrome.
Amazing stuff afforded by the fact that scientists can now walk up to a family with an effected child that otherwise has no family history and observe de novo CNVs (copy number variations). The economics of this has made such approaches which were previously prohibitive to now be highly tractable.
This meaningfully diminishes the fig leaf of "environment" IMO, the argument has always been that in the absence of family history the event was non-genetic. Examples to the contrary are now well extant.
The morality of judgement, while always a difficult one, becomes even more strained when faced with solid molecular genetic underpinnings.