Genetics in 'Mental Illnesses'
The promises of the molecular genetic revolution have not been fulfilled in behavioral domains of most interest to human psychology:
"The hunt for gene effects pertinent to behavioral traits and psychiatric disorders: From mouse to human" Douglas Wahlsten, Developmental Psychobiology, July 2012
The field of behavioral genetics was reviewed in the classic 1960 text by Fuller and Thompson. Since then, there has been remarkable progress in the genetic analysis of animal behavior. Many molecular genetic methods in common use today were not even anticipated in 1960. Animal models for many human psychiatric disorders have been discovered or created. In human behavior genetics, however, powerful new methods have failed to reveal even one bona fide, replicable gene effect pertinent to the normal range of variation in intelligence and personality. There is no explanatory or predictive value in that genetic information. For several psychiatric disorders, including autism and schizophrenia, many large genetic effects arise from de novo mutations. Genetically, the disorders are heterogeneous; different cases with the same diagnosis have different causes. The promises of the molecular genetic revolution have not been fulfilled in behavioral domains of most interest to human psychology.
Genetic Hypothesis Remains Unproven....
Because of psychiatry's influence in the media, most people think that there is a growing body of studies supporting the genetic origin of psychiatric disorders, such as so-called schizophrenia.
In reality, literature supporting a genetic cause for "schizophrenia" has grown sparser over the years. We have fewer and fewer studies claiming a genetic basis. Old ones have become discredited by the hundreds, while new ones are rare indeed....
If there is any pattern here, it is that the genetic hypothesis remains unproven, while the environmental hypothesis has been confirmed repeatedly by the very studies aimed at proving a genetic component.
Peter R. Breggin, MD Toxic Psychiatry: Why Therapy, Empathy and Love Must Replace the Drugs, Electroshock, and Biochemical Theories of the "New Psychiatry"
"Report on Gene for Depression Is Now Faulted" by Benedict Carey, June 17, 2009, The New York Times
"The new report is likely to inflame a debate over the direction of the field itself, which has found that the genetics of illnesses like schizophreniaand bipolar disorder remain elusive."
"Genetics and Epigenetics in Major Psychiatric Disorders: Dilemmas, Achievements, Applications, and Future Scope" by Hamid M. Abdolmaleky et al, Am J Pharmacogenomics 2005