New eugenics, also known as liberal eugenics (a term coined by bioethicist Nicholas Agar), advocates enhancing human characteristics and capacities through the use of reproductive technology and human genetic engineering. Those who advocate new eugenics generally think selecting or altering embryos should be left to the preferences of parents, rather than forbidden (or left to the preferences of the state). "New" eugenics purports to distinguish itself from the forms of eugenics practiced and advocated in the 20th century, which fell into disrepute after World War II. History New eugenics is distinguished from previous versions of eugenics by its emphasis on informed parental choice rather than coercive governmental control. Eugenics is sometimes broken into the categories of positive eugenics (encouraging reproduction among the designated "fit") and negative eugenics (discouraging reproduction among those designated "unfit"). Another distinction is between coercive eugenics and non-coercive eugenics. According to Edwin Black, many positive eugenic programs were advocated and pursued during the early 20th century, but the negative programs were responsible for the compulsory sterilization of hundreds of thousands of persons in many countries, and were contained in much of the rhetoric of Nazi eugenic policies of racial hygiene and genocide. New eugenics belongs to the positive eugenics category. Bioethicists generally consider coercive eugenics more difficult to justify than non-coercive eugenics, though coercive laws forbidding cousin marriage, for example, are widely considered justified. Compulsory sterilization of those deemed unfit is a form of coercive eugenics that has been overwhelmingly rejected in the 21st century, and is illegal under many national and international laws. New eugenics practices New eugenics generally supports genetic modification or genetic selection of individuals for traits that are supposed to improve human welfare. The underlying idea is to improve the genetic basis of future generations and reduce incidence of genetic diseases and other undesirable traits. Some of the practices included in new eugenics are: pre-implantation diagnosis and embryo selection, selective breeding, and human enhancement through the use of genetic technologies, such as embryo engineering or gene therapy. Ethics New eugenics was founded under the liberal ethical values of pluralism, which advocates for the respect of personal autonomy, and egalitarianism, which represents the idea of equality for all people. Arguments used in favor of new eugenics include that it is in the best interest of society that life succeeds rather than fail, and that it is acceptable to ensure that progeny has a chance