  At least some liberal eugenic advocates are aware of this concern and have explored the possibility that our current social norms might be “morally defective” in respect to disability. For instance, Glover defends the permissibility of parental choice within some limits, but he investigates just what counts as a disability. He proposes that a disability involves a functional limitation that “impairs the capacity for human flourishing” (2006: 9), either by itself or in conjunction with social disadvantage. Thus, although racism results in social disadvantage, having dark skin is not itself a disability, because it has no associated functional limitation. Some conditions previously considered disabilities – e.g., achondroplasia – need not be disabilities at all, according to this view (for more on achondroplasia, see Miller 2006; Davis 2010). Glover understands “functional limitations” as a contrast to normal human functioning, a species-based notion that itself involves significant degrees of variation and the matter of setting (rather than discovering) boundaries. As such, “normal” is not purely statistical, but also partly normative (see also Buchanan et al. 2000). Glover recognizes the conceptual messiness of “normal functioning” but still prefers it to alternatives. If an individual prefers a bodily state that might otherwise count as a functional limitation (his example is Asperger’s syndrome), then it isn’t a disability for her (2006: 14); it does not affect her flourishing. He is much less sanguine about blindness and deafness. Both conditions, he suggests, confer significant functional limitations, and although they can certainly allow individuals to have lives of great worth and flourishing – he explores conflicting first-person accounts about going blind and gaining sight to explore the positive sides of the conditions and the negative side of normalizing (2006: 15–22) – he concludes that they are nonetheless disabilities that confer clear disadvantages (related to navigation, safety, etc.). As such, they are disabilities that are understandably acceptable to some, but that ought not be chosen for future children. Such future children, like their parents, might be able to flourish with the condition, but engineering it means intentionally impairing at least some capacities commonly relevant to flourishing. Interestingly, Glover concludes that the Deaf lesbian couple who sought a deaf sperm donor did nothing wrong in conceiving their deaf child (the child cannot be harmed by his clearly worthwhile existence), but he argues they would be wrong in not giving him a cochlear implant if the technology were perfected (2006: 26).