Human genetic modification has begun without a clear consensus on where the moral boundary lines should be placed to insure that the technology of human genetic engineering is not abused. Two principal recommendations have been made for setting the boundaries. The first is between somatic cell versus germ-line correction; the second is between the amelioration of disease and the enhancement of traits. Each proposal involves a distinction and a rule. There is a dilemma in that the first case involves a well-grounded distinction but a dubious rule, while the second offers a more favored rule, but a fuzzy distinction.