Both texts explore the ethical boundaries of human knowledge through positing the idea of man being able to create life. In the form of the creature and the replicants, man is depicted as playing god in the way that they circumvent normal reproductive processes to create life in a way that is described as profoundly unnatural, whether it is through the figure of the "student of the unhallowed arts" of Mary Shelley's imaginings or the scientists who create replicants only to abandon them to perform roles that are dangerous in the extreme. In many ways, these to texts parallel each other in the way that this issue of "playing god" is explored and elucidated.
For Victor Frankenstein, his obsession with creating life is described as a force that literally takes over his life and brings him only unhappiness and sadness as a result. In the way that he abandons his creature so soon after instilling life within him, he abandons his position as father, and this is something that the monster is certainly incredibly bitter about. Note how the title page of the novel includes the following quote from Paradise Lost, a text that is of relevance to both Frankenstein and Blade Runner:
Did I request thee, Maker, from my clay
To mould me Man, did I solicit thee
From darkness to promote me?
Unasked for, both replicants and the creature have been given life, just as Adam was created by God without being asked whether he wanted to be created. Both replicants and the creature have since been abandoned, and inspite their best efforts to be good and to act morally, have only been responded to by violence and anitpathy by humans, both from those that made them as well as other humans they come across. Creating life has massive ramifications, in every sense: morally, ethically, philosophically and psychologically. The consequences of unleashing new life forms on the world in both texts is shown to be disastrous, as both the creature and the replicants cause significant harm and damage as they search for their own identity and a sense of self. Both texts therefore explore the way in which playing god and overstepping normal human processes have massive repercussions.