My memory may be faulty but I feel like Hild came out at a time where there was a whole mini-trend of incest stories. The Game of Thrones TV show started in 2011 and was still in full swing in 2014; Crimson Peak was 2015; The Borgias was 2011-2013; the Mortal Instruments: City of Bones movie was 2013; I am sure there were others I am forgetting. But the early 2010s were a weird time for Hot Sibling-On-Sibling Action in pop culture.