popa_bar_abba: “that no amount of genetic testing will find every genetic disorder, since every one needs to be tested for separately, and it is implausible to test for every one.”
True and no one has to go nuts. But if you marry your cousin, you should go through aggressive testing. If not, do not blame hashem for any misfortunes that may occur.
Dor Yeshorim tests the common genetic mutations. Labs test everything.
Dash: Two recessive genes cause a 25% chance in a family of 4 to have the disease.