Incest (noun)

1. Sexual activity between family members who are too closely related to each other.
2. Any activity between family members that is considered to be morally or legally wrong, such as nepotism.

Origin:

From latin incestus, from incestus, past participle of incestare ("to commit incest"), from in- ("not") + castus ("pure").

Examples:

1. Incest is illegal in most countries.
2. Incest is considered taboo in many cultures.
3. Incest is considered a serious crime, punishable by imprisonment.
4. Incest is a violation of the moral code of many societies.
5. Incest is considered a crime against the family, as well as a crime against society.