Definition & Meaning of "incester"in English

What is the origin of the term "incester" and how is it used?

"incester" is a slang or informal term formed from "incest," referring to sexual activity between close relatives, with the agentive suffix "-er" to label someone who engages in it. The word likely arose in the 20th century as a blunt, descriptive insult or accusation. It is used almost exclusively in hostile, accusatory, or informal contexts, including online discussion or gossip, to condemn or shame someone for incestuous behavior. The term is highly derogatory, morally charged, and never neutral.