My personal theory is that the replicants are basically 100% genetically engineered/cloned human beings, their physical strength or intelligence is boosted by genetic engineering to the limits of humanly possible. Assuming they aren’t shipped sterile by Tyrel they could likely impregnate or be impregnated by “real” humans.
But I see a lot of discussion and reviews where people call them a different species or race or machines etc. I think its because of the confusing descriptions offered by the film, android and replicant, it makes people assume mechanical robots.
I think them being human slaves who have had their genetics fiddled with is KEY to understanding the film, and Deckard’s epiphany. Its a commentary on eternal human nature and failings that with all the technology available slavery is recreated, the film could take place in the Roman empire or early USA really.
The use of terms like replicant and machine by the characters is willful ignorance, if they dehumanize the replicants with these terms they don’t have to face the fact their society is based on outrageous cruelty for its everyday runnings. Not to mention the giant industry that creates them, its in their best interest that the public never realize they are human to keep the money train going. How would Blade Runners feel if they realized they were shooting people running away from sex slavery in the back? This is why the film starts with Deckard an alcoholic, hes close to making that connection and its breaking him mentally.
A piece of evidence used to suggest Deckard is a replicant is when we see in his apartment a lot of old photos, and it is said replicants love to keep photos. I think this is just a piece of irony, ALL humans love taking and keeping photos and mementos! It just shows how dehumanized they have made the replicants, that when they see normal human behaviour in the replicants they call it unusual. Its the cognitive dissonance you always see in slavery or war.
We see Hannibal Chew the engineer who makes eyes, Priss says indignantly “we’re not machines”, Tyrell mentions the replicants are made by “genetic engineers”, we see them bleed, the evidence to me says biological human.
The Voight-Kampff test looks for emotional reactions that are conditioned by living in society, since the replicants first woke up only years before they never learned these. Why would you have an emotional reaction to violence and sex related questions if you have never had morals pounded into you by society? The VK is looking for normal emotional reponses, I’m sure autistics would fail.
And finally while the question of whats real, whats human is important to the film’s theme Deckard being a replicant would make no thematic sense. Deckard is a hunter of runaway slaves who eventually sees through the prejudices his society holds and encourages, and comes to see one of these dehumanized slaves for what she really is and falls in love with her. If he is also one of these slaves the film suffers terribly, Deckard is no longer making a mental leap and a brave risk, hes just doing the logical thing.