The public discourse over biotechnology may be visualized as radiating from one seminal event -- the recombinant DNA controversy of the mid-1970s. This singularly influential episode gave form to a constellation of issues that were subsequently cast as products and processes of the new genetics, including: the manufacture of biological weapons, genetic screening and discrimination, the creation of transgenic animals, genetic modification of human ova, microbial effluent from industrial applications, the deliberate release of genetically engineered organisms into the environment, and human genetic engineering.

Few issues in the field of biotechnology produce as strong a public reaction as the prospect of human genetic engineering. For some individuals, the mere mention of the term conjures up images of a genetically designed race of humans as depicted in Aldous Huxley 1932 novel Brave New World. The idea that some group of humans would set themselves up as the architects of our genetic makeup plays out as some kind of demonic plan whose adherents, should they exist, must be morally deranged.

But the term "human genetic engineering" (HGE) has a broader range of meanings than what is signified above as a centralized program of eugenics applied to fertilized human eggs. The most generalized meaning of HGE is any controlled intervention designed to affect the constitution or function of one or more human genes either directly in the mature organism or indirectly in human germ cells.

The ethical questions surrounding HGE are contingent on which of its several meanings is being advanced. Human gene therapy applies to those uses of HGE that are aimed at curing disease. Proposals introduced by members of the scientific community generally substitute the term "gene therapy" for "genetic engineering" in order to cleanse the term of any negative connotations. Notwithstanding such efforts at conceptual "sterilization" however, the two terms are still used interchangeably by the media and in popular discourse.

Somatic cell therapy is distinguished from germline therapy in that the latter change, unlike the former, can be passed on to future generations. Eugenics is a concept that is much broader than HGE. It means "cleaning up," "purifying," or improving the human gene pool. Genetic engineering potentially can be used to carry out a eugenics program. But there are many other paths to eugenics, including a national policy of selective breeding as well as the widespread use of genetic screening in conjunction with selective abortion.

Sometimes eugenics is defined as "the science of breeding," while elsewhere it is understood as a national policy directed at "purifying" the race. Individual decisions unrelated to a pattern of state-controlled procreation for the purpose of "improving the species" generally do not qualify as eugenic activities. However, if the state supports or mandates genetic screening (amniocentesis) for identification of certain traits of the fetus, and encourages or provides incentives for abortion when one or more traits are discovered, then a eugenics policy is being advanced.