This work discusses two different lines of ethical evaluation for human genetic engineering. The ethical evaluation of these techniques has lately become much more urgent after the development of the CRISPR/Cas9 technique that promises to be a cheap and clean form of human gene edition. This technique may be applied on therapeutic or nontherapeutic grounds, including enhancing or improving human characteristics. From the ethical point of view, in terms of nontherapeutic human genetic intervention, one of these lines of evaluation depends on liberal premises according to which each person should be granted equal status as an autonomous agent. This perspective is compatible with a form of “liberal eugenics,” i.e., with a form of genetic intervention that enhances the autonomy of the persons affected. The second line of ethical evaluation, though, is much more demanding. According to this conception, our nature as human beings has a normative value. Any nontherapeutic genetic intervention is reprehensible under this perspective because it implies the unraveling of the moral guide that comes from our natural inclinations.