I want to agree with you with your point regarding reproducing requirements (yay alliteration), but I simply don't find it practical. Aside from the obvious "how do we set our standards?," there's the problem of unintended consequences. Just like with voter ID laws that many Republicans are trying to push that would make it more difficult for minorities who live in cities (who therefore don't need a driver's license) to vote, for example, setting standards for the ability to reproduce would result in many unintended consequences, the most obvious of which would be the lack of equality among schools in the public school system. Even with low standards for reproduction, anyone entering a public school in a very poor area will inherently be at a huge disadvantage relative to a kid in the stereotypical wealthy suburbs. That child most likely had no choice in which school he/she would attend, so how can we justify imposing such requirements on them to do something so innate in our lives as to reproduce?