Midwest 2-
By the way schizophrenia can be inherited. Not just as you say “The only sure way to be at risk is to marry the identical twin of someone who has been diagnosed with schizophrenia.” It is not small enough a chance to worry. It can be genetic,or a fluke or conditions in the womb. or it can happen because of life choices someone makes (drugs ect) Schizophrenia is quite severe and should be taken seriously and the person NEEDS HELP. Dont say that “if dor yeshorim isnt testing for it you shouldnt worry. Dor yeshorim mostly tests for JEWISH GENETIC diseases and ones prevalent to many in the Jewish community (because of where they came from).
Other thing are genetic (diabetes is one of them. It is normal to test children of certain types of diabetes, especially when the diabetes is severe and not due to weight or other conditions ect)
Some things are definitely not (as far as current data): spina bifida, epilepsy