  The reproductive choices that prospective parents are encouraged – or morally required – to make regarding their offspring are choices about selecting or enhancing their children or selecting the best they can have. All involve comparisons about traits that contribute to better or worse lives. But deciding which traits are positive, and of those, which are better than others, is a task far from simple. Critics point to the difficulty of ranking the expected well-being of future possible lives, given 1) disagreements about what traits are positive and negative, and the need to contextualize such traits in a particular environmental or societal context or family situation, and 2) the reality that most embryos will have a complex mixture of positive and negative traits making meaningful pairwise comparisons very difficult (de Melo Martin 2004; 2017; Parker 2007).