NIMH says that by studying the genetics of the early onset cases, insight has been gleamed into genes linked to other genetically complex disorders like some cancers, Alzheimer's and Crohn's diseases. 
They suggest that studying children with schizophrenia and their families may help them discover the molecular roots of the illness, since genetically-linked abnormalities is twice as high in childhood-onset cases than it is in adult-onset cases
A very large genetic study  was conducted by Wellcome Trust , with psychiatric genetic researcher, Dr. Nick Craddock helping to recruit patients. Genes studied that have been particularly associated with both schizophrenia and bipolar disorder were DAOA, DISC1, NRG1 and DTNBP1, as well as possibly GABRB1 (GABA), and GRM7 (glutamate) and SYN3 (synapsinIII).
One associated gene of particular interest was KCNC2 which is associated with episodic central nervous system disease, including seizures, ataxias, and paralyses, and which the researchers surmise may also extend to episodic disturbances of mood and behavior.
The seven illnesses with genetic links found in that large study were: bipolar disorder, coronary artery disease, Crohn’s disease, hypertension, rheumatoid arthritis, and Type 1 and Type 2 diabetes.
Dr. Craddock's hope is that eventually, with better understanding of the actual physiology underlying each case of “schizophrenia” and “bipolar disorder”, many of these cases will receive a completely different diagnosis. His hope is that treatment can start being geared to the actual underlying causes of the illnesses rather than just treatment for the symptoms.
When we add in genetic links between autism and schizophrenia (such as microdeletion and microduplication at 16p11.2), and links to mitochondrial dysfunctions, and autoimmune disorders such as Celiac , we can see that science has just discovered the tip of the iceberg.
At least, they are now looking at that iceberg.
References and Notes
[*] Note that structural abnormalities of the brain are considered to be physical, not a psychological issue. They are studied by scientists and medical doctors – not therapists and psychologists.
 Childhood-Onset Schizophrenia: An Update from the National Institute of Mental Health.
 Genome-wide association study of 14,000 cases of seven common diseases and 3,000 shared controls (Nature, Vol 447, 7 June 2007)
 Largest ever study of genetics of common diseases: Wellcome Trust Case Control Consortium and genetics of seven common diseases
 New Partnership with Leading Bipolar Disorder Research Professor
 Association of Schizophrenia and Autoimmune Diseases (Am J Psychiatry 163:521-528, March 2006) Found schizophrenia linked to 12 autoimmune disorders including thyrotoxicosis, celiac disease, Sjogren's syndrome. The authors concluded with the hope that further study could “advance understanding of pathogenesis of both psychiatric and autoimmune disorders.”
Genetics and Epigenetics:
- Specific Genes Inherited from Both Parents May Lead to Type of "Schizophrenia" (How schizophrenia can skip a generation)
- What are some genetic causes of psychosis?
- What is Epigenetics
- Brain Health: Nutrition and Epigenetics
- Mitochondrial Dysfunction and Psychiatric Symptoms