The gene pool has not changed significantly over the past 5,000 years, but human society and individual opportunity have been transformed. Moreover, history is littered with supposedly scientific pronouncements about the limits of women, African Americans, Southern Europeans, Asians, and Jews. Science has done a singularly poor job when it has sought to define limits on human potential. Clearly, some DNA changes are unquestionably negative mutations, destroying the function of a crucial protein. These are serious goals, not to be lightly dismissed.
Safety is, of course, a major concern.
Given the subtleties of human physiology, quick genetic fixes are likely to do more harm than good. But there will come a time when we can do such things safely, and it's not too soon to ask whether we should. If we cross that fateful threshold, I don't see how we can ever return. I part company from some of my colleagues here. While I'm strongly opposed to laws limiting scientific investigation, I would support a ban on modifying the human germline.