Medical Genetics For example, first-degree biological relatives of persons with schizophrenia have a ten times greater risk of developing the illness than members of the general population. Also, in the United States more schizophrenic patients are born in the winter months of January to AprilMedical Genetics For example, first-degree biological relatives of persons with schizophrenia have a ten times greater risk of developing the illness than members of the general population. Also, in the United States, more schizophrenic patients are born in the winter months of January to April