- Consanguinity may contribute to the incidence of schizophrenia in offspring despite the usually accepted polygenic model of schizophrenia inheritance. Bedouin Arab families in southern Israel have a high rate of cousin marriages as do families throughout most Arab societies. We studied consanguinity in the parents of schizophrenic patients admitted in a defined catchment area of southern Israel, compared to a control group of parents of all infants born to Bedouin mothers in this catchment area. There was a small but significant increase in the rate of cousin marriages among the parents of schizophrenia patients compared to parents of infant controls. These results are consistent with claims that inbreeding can contribute to the incidence of schizophrenia even as a polygenic illness. However, the absence of a better matched control group limits confidence in the results.