Below I repeated the contention that while schizophrenia is a genuine biologically rooted behavioral disease which can not be cured through will, many forms of addiction are not. That is why the genetics of schizophrenia are of such great interest, if the biological pathways of the pathology can be elucidated presumably a cure may be found. Unfortunately finding the genes is easier said than done, see Schizophrenia: The Mystery of the Missing Genes.
We can't even provide an empirical definition of "schizophrenia". Looking for the etiology of a condition you can't define is usually a waste of time - unless the causes are both clear and specific, you'll be so swamped by the noise created by your categorization errors that most signals will be washed out.