Morgaine on the other hand develops feelings for her half first cousin Lancelet and they become sexually involved. Morgaine also commits incest with her step son Accolon.
The movie The Blue Lagoon also insinuates incest between siblings but here cousins. After being marooned on an Island, two cousins grow up as lovers. They have sexual intercourse and have a child.
Other examples of cousin incest in literature are Jane Austen’s Mansfield Park (Fanny marries her first cousin Edmund) and Thomas Hardy’s novel Jude the Obscure where cousins Jude Fawley and Sue Bridehead pine for each other finally submitting to each other sexually.