Within the next few years scientists will almost certainly have pieced together a broad map of the major gene locations on the twenty‐three human chromosomes. The rapid unfolding of this new knowledge raises new questions: What limits, if any, should be imposed on its acquisition? Who should control the wealth of resulting data? How should it be used? If, because of a deep‐seated need for certitude, many persons are likely to perceive a positive gene probe test as an indicator of (...) biologic destiny, probes may acquire a misleading status in our medical armamentarium. (shrink)