One of the most frequent subjects in the science fiction canon is the creation of artificial life, specifically an artificial human being, or android. This is a subset of a more general literary theme involving man's striving for something beyond ordinary experience: his wish to achieve the impossible and to accomplish what only God or the gods should properly do. Perhaps it's unsurprising that these experiments are often shown to backfire. Man attempts that which is past the bounds of what is permitted, and he is punished for it.
The prototype in western literature of this scenario is Mary Shelley's Frankenstein, in which a scientist creates an artificial being but then refuses to take responsibility for his creation. But beyond this failure or sin of Viktor Frankenstein, the point of the story is to blur the distinction between the artificial and the real. The Monster, though created in a laboratory, has the characteristics of an actual person. He has not only a physical life but a mental and emotional one as well. The opposition between nature and artifice becomes, in Shelley's hands, a means to explore the dysfunctional dynamic that exists among humans in the real world, in which those who are different are marginalized and rejected by society. The artificial being becomes a symbol of Otherness. The distinction between the natural and the artificial is meaningful only in a negative sense, as a metaphor for the illusion of differences among people by which one group discriminates against or oppresses another.
In more recent science fiction, the distinction between nature and artificiality is extended to the depiction of androids who don't even know that they're artificial beings, as in Philip K. Dick's Do Androids Dream of Electric Sheep? (and the film based on it, Blade Runner) and the episode "Requiem for Methuselah" from the first Star Trek series.
In Frankenstein, the Monster's "horrific" appearance differentiates him from ordinary humans. Shelley's point is that discrimination for this reason, that of one's physical nature, is shallow, unrealistic, and cruel. But in these later examples, the fact of an android being indistinguishable both physically and mentally (including in their consciousness or self-perception) from a "real" person is a qualitatively new presentation of the basic metaphor about Otherness. The additional question is the more purely scientific one of whether there is any difference at all between the "natural" and the "artificial," with regard to androids or anything else.