The Genetic Theory of Schizophrenia: A Critical Overview

(Link to a 1999 article pdf published in Ethical Human Science & Services, 122(2), pp. 119-145. https://psycnet.apa.org/record/2000-05766-001)

Link to article pdf HERE

Abstract

Examined family, twin, and adoption studies supporting the widely accepted belief that schizophrenia is acquired, at least in part, on the basis of genetic factors. Emphasis is placed on twin and adoption studies since results from family studies are consistent with a genetic or an environmental causation. The author contends that the acceptance of a genetic component to schizophrenia derived from twin and adoption studies is based upon unproven theoretical assumptions. It is argued that twin and adoption studies have suffered from many other methodological problems as well. It is concluded that the total weight of evidence from family, twin, and adoption studies in favor of the genetic theory of schizophrenia is inconclusive, and that this theory should therefore be rejected until new evidence is presented in its favor. In addition, this analysis predicts that a gene for schizophrenia will not be found, because it does not exist. (PsycINFO Database Record (c) 2017 APA, all rights reserved)