In answer to questions raised by practitioners, an ethics of genetic screening is located in a tension between liberty and responsibility in three respects: (1) to nature and biological processes; (2) to the disposal of human life; and (3) to the relation of persons to society. Under (1), the obligation to pursue research, fundamental as well as applied, is affirmed, offering the benefit of economy with fetal life, but requiring discrimination between the beneficial, the trivial, and the bizarre. Under (2) the abortion question, when relevant to diagnosed abnormality, is discussed, not in the language of conflicting rights, but of the relation of duties to interests. Under (3) the familial and social dimensions of screening raise questions of the disclosure of information and the keeping or extending of confidences. Last comes the value placed on truth in two related areas of developing practice. In infertility treatment, the donors of gametes are required to remain anonymous. Gene tracing through families requires for its effectiveness some correspondence between assumed identity and genetic identity. This conflict of social policies should be resolved.