Suppose that it becomes possible to control the genetic traits of our descendants, and thus treat them as a product which can be engineered to our liking. Employing a Kantian vocabulary, Habermas says that this is a kind of intervention which should only be exercised over things, never over persons. In The Future of Human Nature, Habermas develops a version of a common objection to genetic engineering – that it would involve treating humans as means rather than as ends. His formulation of this argument is important because he makes the novel claim that there is a somatic basis to our ethical freedom. We are embodied individuals and in order to regard ourselves as free and equal members of a community of similarly embodied individuals, we need to stand in a certain relationship to our own unchosen physical characteristics. The prospect of choosing the positive genetic characteristics of another person threatens to change the nature of that person's relation-to-self in a way that undermines his or her potential to become fully autonomous.

A number of philosophers working within the liberal tradition have argued that, for certain purposes, genetic selection and enhancement of embryos may be consistent with liberal principles. Liberal eugenics distances itself from the dark history of authoritarian, state-directed eugenics programmes, but asserts that parents' rightful freedoms entitle them to pursue some eugenic goals with respect to their children.