eugenics (yōōjĕn´Ĭks), study of human genetics and of methods to improve the inherited characteristics, physical and mental, of the human race. Efforts to improve the human race through bettering housing facilities and other environmental conditions are known as euthenics.
Sir Francis Galton, who introduced the term eugenics, is usually regarded as the founder of the modern science of eugenics; his emphasis was on the role of factors under social control that could either improve or impair the qualities of future generations. Modern eugenics is directed chiefly toward the discouragement of propagation among the unfit (negative eugenics) and encouragement of propagation among those who are healthy, intelligent, and of high moral character (positive eugenics). Such a program involves many difficulties, especially that of defining which traits are most desirable.
The first half of the 20th cent. saw extreme coercive application of such principles by governments ranging from miscegenation laws and enforced sterilization of the insane in the United States and other nations to the Holocaust of Nazi Germany. Regulated eugenics continues in some parts of the world; China enacted restrictions on marriages involving persons with certain disabilities and diseases in 1994.
In the United States in recent years, interest in eugenics has centered around genetic screening (see genetic testing). It is known, for example, that hemophilia, albinism, and certain structural abnormalities are inheritable. Family gene maps, called pedigrees, can help families with serious diseases avoid having children with the same diseases through genetic counseling, and, increasingly, prospective parents can be tested directly for the presence of undesired genes. If conception has occurred, tests such as amniocentesis and chorionic villus sampling can be used to detect certain genetic defects in the fetus. Embryo screening can be used in conjunction with in vitro fertilization prior to pregnancy to test embryos for genetic abnormalities; only those found free of defects are implanted and allowed to develop.
See J. H. Bennett, Natural Selection, Heredity, and Eugenics (1983); D. J. Kevles, In the Name of Eugenics (1985); M. B. Adams, ed., The Wellborn Science: Eugenics in Germany, France, Brazil, and Russia (1989); E. A. Carlson, The Unfit: A History of a Bad Idea (2001).