... than DZ twins who only share 50% of their genes, although the concordance rate was not 100%. This certainly highlights the huge influence genetics have on inheriting the condition however, if genetics were the sole cause we would expect the MZ twins to have 100% concordance which leaves the possibilities for factors. Although MZ twin studies have the advantage of controlling for genetics they are not unable to control the environment. A solution to this would be to study MZ twins who have separated. Twin studies show similar concordance rates even when they have been separated but this evidence is limited due to the fact that the samples taken in these studies are usually rather small. There is further support from adoption studies for the genetic explanation of schizophrenia. Tienari found that children who had been adopted away from a schizophrenic biological mother were still more likely to get it than children ...

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