Yes, twin studies have often been trumpeted to demonstrate that schizophrenia has a strong genetic basis. However, we've yet to find any actual genetic variatio

Yes, twin studies have often been trumpeted to demonstrate that schizophrenia has a strong genetic basis. However, we've yet to find any actual genetic variation strongly associated with schizophrenia, which, with such a high rate of concordance, should be a snap. Twin studies themselves are suspect in a number of ways - the assumption of environmental equivalence between twins and the general population is suspect, for example. Fraternal twins also show higher concordance than siblings, even though their genetics should be the same.