English

Noun

twincest ‎(uncountable)

1. (chiefly fandom slang) Incestuous sexual relations between twins, or siblings who look very similar.
   • 1985, Joseph Hansen, A Smile in His Lifetime, New American Library, page 64:

     This one's about gay brothers. I'm calling it Twincest. Nice, no?

   • 1998, Film Review: Special: Year Book 1997/98, Visual Imagination Ltd., page 117:

     As 'twincest' is in (a trend started by Parker Posey and Josh Hamilton in The House of Yes, to be released in the UK in 1998)...

   • 2007, Rachel Kramer Bussel, Best Sex Writing 2008

     These pieces you might very well be able to relate to even if you've never been horny for twincest, had an affair, or been a black man...

   • 2013, John Lancaster, "When did you get hooked?", London Review of Books, vol. 35, no. 7:

     In the course of one of his climbs, he hears adult voices through a high window, goes to investigate, and comes across Jaime and Cersei energetically engaged in (to use a neologism popular with fans) twincest.