Blade Runner

The film Blade Runner takes place is some-what different from the novel we read . For example the death of Miss Luft , were deferent from how it appeared in the novel . To sum up the movie special robots were created to act like servants , these robots are know as  Replicants. There called Replicants because they share similar features to humans but has no emotions. Nevertheless after some of the Replicants got away and came to earth,it became Deckard mission to find them and kill them. One major theme I see throughout the novel and the movie is What are Humans? What make us a human being? The purpose of the Replicants and androids were to be more of a human begin than humans. The Replicants in Blade Runner were design to have no type on emotion but it were clear that they do have emotions just as humans from the scene where Rachel was asked Deckard questions about her existence. One question I still have , Why did Deckard tell Rachael that she is a Replicant? Why not just keep it to his self ?