  Despite their confidence, there is reason to think there will be significant disagreement in both steps. A theory of well-being that is acceptable to most might be so abstract as to fail to offer any significant help, and then the matter of determining how traits or conditions in question are related to expected well-being – such that we can do a comparison and select the best – will be even more difficult (Parker 2007). Parents who see value in a wide variety of ways of being in the world – both for the individual, and for society as a whole – may welcome children who have traits that are not standardly considered advantageous. Consider, for instance, positive accounts about raising children with Down syndrome (Berube 1998; Estreich 2011; Kaposy 2018), and even profound cognitive and physical disability (Kittay 1999). Indeed, as Sparrow (2007) has pointed out, on any of the accounts of wellbeing that Savulescu and Kahane consider, their proposal to choose the best child will turn out to have either counterintuitive or incoherent results. For instance, prospective parents who have a hedonist conception of wellbeing would be justified in choosing –indeed obligated to do so – the child whose brain chemistry is more likely to cause feelings of pleasure. Similarly, on a desire-fulfillment account, parents would have reasons to choose children who will grow up to have less ambition or curiosity as their preferences will be more likely satisfied, and thus would have better lives.