Schizophrenia is thought to arise from heterogeneous etiologies. There is evidence that some schizophrenia is genetically linked and that the manifestations of that genetic liability are not limited to schizophrenia, but may include schizotypal disorder or neuropsychological abnormalities. In a recent study, unaffected siblings of schizophrenic patients had similar neuropsychological abnormalities to their affected sibling but to a lesser degree.