Nazi eugenics was a program created by the Nazis (a political group in Germany during World War II) to try and create a better race of people by getting rid of people they thought weren't perfect. They thought they could change people's genes (the things inherited from your parents that make you who you are) to make them better by eliminating the genes they didn't like. This involved removing people from the population who they thought were weak or disabled, or who had different beliefs or skin color. They wanted everyone else to have the qualities they thought were perfect and that everyone else should have the same traits. It was a terrible plan and ended with a lot of people getting hurt or killed.