The term eugenics, meaning "wellborn," was coined in 1883 by Francis Galton, the scion of an upper-class British family and a cousin of Charles Darwin. Galton wrote that he intended it as "a brief word to express the science of improving the stock, which...takes cognizance of all the influences that tend...to give the more suitable races or strains of blood a better chance of prevailing speedily over the less suitable than they otherwise would have had." Included among the "less suitable" strains of blood were "paupers," "drunkards," and the "feebleminded," loosely defined. So, race and class prejudices were there from the start.
Genetics did not yet exist as a science, though the Czech monk Gregor Mendel published his classic paper in 1865. Mendel's laws of inheritance only became widely known after the paper was rediscovered in 1900. Not long after that, geneticists began to examine patterns of inheritance of human traits such as hair or eye color and of diseases. By constructing family pedigrees, they showed that similar regularities exist in the way human traits are passed from parents to children as Mendel observed while studying the transmission of flower color and the shape of seeds in pea plants.
Thus, they noted that quite a number of inborn human diseases are not noticeable in the parents of children who exhibit the conditions, but do occur in other members of the parents' families. Adopting a term coined by Mendel, such diseases are said to follow a recessive pattern of inheritance. In the language of modern genetics, we say that for people to manifest a recessive condition, they must inherit two copies of the relevant gene, one from each of their parents. The reason the parents themselves do not manifest the condition is that they "carry" only one copy of that gene. They are referred to as carriers.
Most inherited diseases are of this nature. They surface sporadically in children whose parents do not manifest the condition and often do not even realize that it runs in their family until they have a child who exhibits it. Geneticists assume that all of us carry several genes, associated with recessive conditions, which would be debilitating, or even lethal, had we inherited the associated gene from both our parents.
Once most "bad" genes were understood to lurk within healthy people, even eugenically-minded geneticists realized that there is no way to cleanse the human "gene pool" of most "deleterious" genes. The people who manifest the associated conditions represent only the tip of the iceberg; preventing them from having children would hardly affect the prevalence of these genes in the population. This realization eroded support for the eugenic involuntary sterilization laws, which the majority of U.S. states had enacted in the early part of the 20th century.
Eugenic aspirations, however, were energized anew during the 1970s, when it became possible to assess the health status of fetuses by means of ultrasound imaging and genetic tests. By now, assessing fetal health has become a routine part of prenatal care and the impulse to get rid of "bad genes" has been reframed in the currently more acceptable rhetoric of "choice" -- in this case, the choice of tests which might lead to the decision to terminate a wanted pregnancy. The fact that disease-linked genes usually lie buried within healthy carriers has been a major impetus for developing techniques and policies for carrier detection. In addition, a new industry is being built to devise ways to detect genes "for" conditions most people never knew existed, and hence weren't worried about. These transformations are not surprising in view of the medicalization and geneticization of current thinking about all aspects of health and social life. Proposals are frequently voiced for population-wide screening for the most common forms of the gene linked to cystic fibrosis and for screening specific populations, such as African Americans, Mediterraneans, or Jews, for genes these sub-populations harbor at greater frequencies than do other people.
Given our current ethos of "choice," there are no rules about what the carriers, once identified, are to do with the information. Fiscal pressures from insurers as well as our society's "healthism" and "ableism," however, make it likely that most couples will try to avoid to knowingly bear a child predicted to exhibit the condition for which both parents are carriers. So far, no prenatal genetic tests are compulsory, but since future parents are usually required to sign a refusal form if they decline a test, the "choice" not to test is clearly constrained by the prevailing ethos.
Since none of us know what evils may lurk in our genes, prospective parents can hardly escape the ever-widening net of fears being cast over the health of their future children. Most parents-to-be do not realize that the information prenatal tests offer is often uncertain and rarely useful. Nor are they usually warned of the anxiety the tests themselves tend to engender. The choice ideology that is part of the thinking of those of us who support abortion rights keeps many of us from acknowledging the one-sidedness of our "choice" to assent to predictive testing. Many of us don't pay for these services out of pocket, so that our "choices" are constrained by the cost/benefit calculations of our insurers. They are, of course, also limited by the calculus of profit that determines which tests are developed, and how (and at what price) they are marketed.
To exercise genuine choice, we would need to shift the frame of reference within which we think about illness and health and face up to the realities of human variability rather than narrow the definition of who is an acceptable human. Life is chancy, especially when it comes to procreation, which begins with the chance encounter of one of several possible eggs with one of many millions of sperm. Try as we will, we can shield our children against only a few, foreseeable risks. Far better to move away from the concern with personal and individual "choice" and try to improve the social and economic conditions everyone needs to live healthfully. Most people are at greater risk of becoming disabled by environmental hazards or accidents -- at work, at home, on the street -- than they are from the genes they inherit from their parents. Securing everyone's access to clean air and water and to adequate amounts of nutritious food would be much more effective in reducing ill health than predictive tests and genetic interventions can be.