The study was conducted by researchers at the Center of Neuropsychiatric Schizophrenia Research at Copenhagen University Hospital performed a twin cohort study with both identical and non-identical twins.
"(T)hese studies provide unique comparisons when it comes to genetics. Identical twins have 100 percent of their genome in common, whereas non-identical twins share roughly 50 percent of their genes," Robin Andrews explained.
Previous research had shown that, when it comes to schiziphrenia, 41 to 61 percent of identical twin pairs are affected by schizophrenia. In non-identical twin cases, 0 to 28 percent are affected.
In this study, statistical analysis was performed on a mix of approximately 32,000 twin pairs, both identical and non-identical, all born up to the year 2000. About 1 percent of them had developed schizophrenia and 2.5 percent of them had schizophrenia-like disorders.
When it came to identical twins, if one was afflicted, there was a 33 percent chance the other would be too. In non-identical twins, this link dropped to 7 to 9 percent. While they did not identify the genes responsible, they did determine that 73 percent of schizophrenia-like disorders, and 78 percent of schizophrenia cases, were caused by genetics.
Ultimately, additional research will need to be performed in order to confirm these findings.