>>55128759It's a great narrative device for tragic stories. my favorite usage is as a desperate last resort, like a symbolic expenditure of generational power built up over centuries, which also ends the genetic line. This happens in Volsungsaga where a clan is destroyed and the last surviving brother and sister respectively become prisoner and wife of the conquerer.
So the sister Signy goes to her brother Sigmund in prison and gets pregnant by him. As the culmination of the Volsung line, incest baby Sinfjötli is capable of incredibly great deeds and successfully avenges his family, but ultimately is doomed to die as the end of his bloodline, never to have children of his own.
