What similarities can be drawn between the novels Frankenstein and Never Let Me Go?
This is a very interesting question. Both novels deal with a central idea that humanity is a somewhat fluid concept, that can be redefined and recontextualized based upon a number of different considerations. In Mary Shelley's Frankenstein, Victor Frankenstein decides to create life from dead flesh and human body parts, and creates a being who resents his very creation and his creator. Frankenstein's "monster" is human in every sense of the word, with human emotions, thoughts and desires, but his hideous appearance likens him to a monster. He will never be accepted by society and is considered less than human.
In Kazuo Ishiguro's Never Let Me Go, there is a wider plan at work, much larger in scale and scope than Frankenstein's singular experiment: there is a nationwide experiment occurring in England to produce human clones who can be harvested for organs. There is an odd inversion of the Frankenstein imagery at work in Ishiguro's novel: instead of body parts being used to build a human, usable body parts are the result of the creation of humans. The clones look and seem perfectly normal; but there is a dilemma over whether or not they have souls, and whether they are wholly and truly "human."
In Frankenstein, monstrousness is based upon outward appearances; in Never Let Me Go, the monstrousness is beneath the surface. In both books, people who have scientific origins based upon artificial means of reproduction become living humans with unique thoughts and emotions.
The first, and most obvious, parallel is between Frankenstein's monster and the clones in Never Let Me Go. Not only are both "abominations" of a kind, in that they are creatures that are not naturally born, but the outside world also views them with suspicion because of that fact. The villagers react to Frankenstein's monster with fear and hostility; the teachers in Never Let Me Go (Miss Emily, for instance) tell the children that they are "afraid" of the children and live in "dread" of them. Even though the clones appear like normal people and are thus not feared in the way that Frankenstein's monster is, the mere fact that they are clones arouses dread in other people.
Another parallel, although not as stark, consists in the attitude towards knowledge and information. The teachers at Hailsham attempt to protect the children by not giving them complete information about themselves. The character of Victor Frankenstein tells the reader that he himself is an example of how dangerous knowledge can be. We also see how the monster's knowledge proves dangerous to others and how the clones' knowledge proves to be devastating for them.
At a more abstract level, both novels raise the philosophical question about whether or not scientific progress is ultimately better for society, a question that Jean-Jacques Rousseau answers in the negative in his First Discourse. Both the novels share a Rousseau-esque skepticism about the promise of scientific progress.
There are many connections one could draw between the two novels. For me, the one that sticks out is how both books commodify the body and problematize the nature of humanity. In Frankenstein, for instance, the monster is assembled, like a machine, from various body parts Frankenstein is able to acquire; once the monster is brought to life, however, it is clear that his monstrous shape does not mean that his feelings are also monstrous. Much of the middle of Shelley's novel is given over to the monster's education; he "learns" to be a monster in part because of the way people react to how he looks.
In "Never Let Me Go," we have a similar attitude towards the body; although the "donors" are valued solely for the viability of their organs, like the monster in Frankenstein, they are clearly more than the sum of their parts. Both books are, in a sense, novels of education; the lesson the monster learns from the De Laceys is that his ability to empathize with their troubles will not make them accept him; the lesson Kathy and Tommy learn is that "true love," whatever that may be, will not earn them the deferral that will save them from their fate as organ donors. Both books argue that our bodies do not determine our identities, but that, in society, what we are is often more important than who we are.