Here's why:
* It's a proper noun: "Genocide" is a specific historical event, similar to "World War II" or "the Holocaust." These events have a singular meaning and are treated as proper nouns.
* It's a technical term: "Genocide" is a legal term, referring to the deliberate and systematic destruction of a group of people. Capitalizing it reinforces its legal and historical significance.
Example:
* "The Rwandan genocide was a horrific event that resulted in the deaths of hundreds of thousands."
However, you do not need to capitalize "genocide" when using it as a general term:
* "The United Nations has worked to prevent genocide around the world."