Genetic screening is a particular activity within the broad domain of medical screening. Screening should be distinguished from the traditional medical act of surveillance. Heterozygote screening – in its general form – is a search in a population for persons at risk for genetic disease in themselves or their descendants, in either the universal or a particular environment. The efficiency of a genetic screening method is related to its specificity and its sensitivity. Correct classification of screened individuals by means of their test result is obviously important. The direction of all subsequent medical and genetic counseling is dependent on the genotype assigned. A serious gap often exists between potential and achievement of a particular genetic screening program. The fault usually lies in the organization of the program. Students are taught as a matter of course the received doctrine about the physical world; they are not taught biology and genetics, with a corresponding emphasis.