Dysgenics

Dysgenics (also known as cacogenics) is the study of factors producing the accumulation and perpetuation of defective or disadvantageous genes and traits in offspring of a particular population or species. Dysgenic mutations have been studied in animals such as the mouse and the fruit fly. The term dysgenics was first used as an antonym of eugenics—the social philosophy of improving human hereditary qualities by social programs and government intervention.

Read more about Dysgenics:  Intelligence Dysgenics, Dysgenics For Other Traits, Genetic Disorders, Other Counter-acting Effects, In Fiction