Another, perhaps more visible, backdrop for the enhancement ethics literature is the history of the 20th century eugenics movement, which attempted to “breed better people” and “improve the human gene pool” through socially biased reproductive controls and inducements (Wikler 1999).  This background prompts questions about the cultural authority of science and the social values it can perpetuate, and raises fears of slippery slopes that can lead to egregious forms of oppression, by providing a vivid recent counter-narrative to endorsements of enhancement as a way to fulfill our obligations to future generations (Sparrow 2011; Selgelid, 2013). The eugenics backdrop tends to skew the burden of proof the other way in the debate, towards a more “precautionary” stance that gives advocates of enhancement the burden of distinguishing their proposals from old style eugenics in order to defend the parts of that ideology that they share (Kitcher 1997; Harris, 2007; Agar 2004).