Critics have had a tough time categorizing Kindred ever since the book first came out. Octavia Butler has gone on record saying that she thinks of the book as belonging to the fantasy genre. Other people call it a sci-fi book because Butler is mostly known for her sci-fi fiction. There are even others who just want to call the book "literature" because it deals with heavy themes like race and misogyny in a complex way. So that's why it's best to just hedge your bets and call it, like we do, "sci-fi fantasy literature." Everybody happy?