Not sure that everyone will agree this is science fiction, but it is. The parents of a child with cancer either clone or genetically engineer an additional child to use for spare parts for the first. The movie deals with emotional and legal aspects as the cloned child fights for her rights. Basically a chick flick, but still SF.

"There is a lot of money tied up in this film and people expect to hear a boom when something blows up, so I'll give them a boom."

George Lucas as quoted by Harlan Ellison's WATCHING