The discussion of "designer babies" often revolves around gender or hair color, but as Nita Farahany and Marcy Darnovsky explore, the medical debate is far more complicated. Farahany is Professor of Law and Philosophy, Director of Institute for Genome Sciences and Policy, Duke University; Member, Presidential Commission for the Study of Bioethical Issues. Should we screen embryos for disease? Should we make genetic modifications? These considerations raise ethical concerns and call into question the validity of surrounding research. The lack of regulation and oversight make this particular biotechnology frightening to some, while the potential for disease eradicating techniques excites others. But how far is too far? What are the major scientific and ethical hurdles to assuage the skeptics? Marcy Darnovsky is the executive director of the Center for Genetics and Society. Nita Farahany is professor of Law and Philosophy and director of the Institute for Genome Sciences and Policy at Duke University. She is a member of the Presidential Commission for the Study of Bioethical Issues.