1、Eugenics is the study of or belief in the possibility of improving the traits of the human species or a human population, especially by such means as discouraging reproduction by persons having genetic defects or presumed to have inheritable undesirable traits (negative eugenics) or encouraging reproduction by persons presumed to have inherited desirable traits (positive eugenics).

2、Many countries have histories with eugenics policies, some more explicit than others, and the eugenics movement is often seen as constituting a powerful force but one that lost credibility during the Nazi era.