Why are science and the issue of responsibility relevant?
Think about issues we face in medicine and science such as transplants (including animal to human), life support, and cloning.

How do we know about science in general?
 Look at the preface (the story of the novel's inception and the references to the work of Erasmus Darwin).  We also have two different scientists, working in two different areas.

Good intentions (always mixed with personal satisfaction) doesn't always mitigate the results.  Below are two excertps, both indicating intentions:

 Walton:  "I may there [North Pole] discover the wondrous power which attracts the needle; and may regulate a thousand celestial observations, that require only this voyage to render the seeming eccentricities consistent for ever.  I shall satiate my ardent curiosity with the sight of a part of the world never before visited, and may tread a land never before imprinted by the foot of man.   There are my enticements, and they are sufficient to conquer all fear of danger or death, and to induce me to commence this laborious voyage with the joy a child feels when he embarks in a little boat, with his holiday mates, on an expedition of discovery up his native river.  But supposing all these conjectures to be false, you cannot contest the inestimable benefit which I shall confer on all mankind to the last generation, by discovering a passage near the pole to those countries, to reach which at present so many months are requisite; or by ascertaining the secret of the magnet, which, if at all possible, can only be effected by an undertaking such as mine."  (Letter 1)

 Frankenstein: "No one can conceive the variety of feelings which bore me onwards, like a hurricane, in the first
enthusiasm of success.  Life and death appeared to me ideal bounds, which I should first break through, and pour a torrent of light into our dark world.  A new species would bless me as its creator and source; many happy and excellent natures would owe their being to me.  No father could claim the gratitude of his child so completely as I should deserve theirs.  Pursuing these reflections, I thought, that if I could bestow animation upon lifeless matter, I might in process of time (although I now found it impossible) renew life where death had apparently devoted the body to corruption." (Chapter IV)

Some of the indications that the novel functions as a warning are:

parallels with Prometheus myth, Samuel Taylor Coleridge's "Rime of the Ancient Mariner,"  and John Milton's Paradise Lost

Prometheus:

subtitle (or, The Modern Prometheus)
 

"Rime of the Ancient Mariner":

Walton: "I am going to unexplored regions, to ‘the land of mist and snow;' but I shall kill no albatross, therefore do not be alarmed for my safety, or if I should come back to you as worn and woful as the ‘Ancient Mariner?'" (Letter 2)

Frankenstein: "‘Unhappy man!  Do you share my madness?  Have you drank also of the intoxicating draught?  Hear me, --let me reveal my tale, and you will dash the cup from your lips!"
. . . You seek for knowledge and wisdom, as I once did; . . . when I reflect that you are pursuing the same course, exposing yourself to the same dangers which have rendered me what I am, I imagine that you may deduce and apt moral from my tale; one that may direct you if you succeed in your undertaking, and console you in case of failure."  (Letter 4)

* * * * * * * * * * * * Frankenstein:  "Learn from me, if not by my precepts, at least by my example, how dangerous is the acquirement of knowledge, and how much happier that man is who believes his native town to be the world, than he who aspires to become greater than his nature will allow."  (Chapter IV)
 

Paradise Lost

Epigram: (quotation from PL): "Did I request thee, Maker, from my clay / To mould Me man?  Did I solicit thee / From darkness to promote me?-- [X. 743-5]

Creature (as told by Frankenstein): "‘But "Paradise Lost" excited different and far deeper emotions.  I read it, as I had read the other volumes which had fallen into my hands, as a true history.  It moved every feeling of wonder and awe, that the picture of an omnipotent God warring with his creatures was capable of exciting.  I often referred the several situations, as their similarity struck me, to my own.  Like Adam, I was apparently united by no link to any other being in existence; but his state was far different from mine in every other respect.  He had come forth from the hands of God a perfect creature, happy and prosperous, guarded by the especial care of his Creator; he was allowed to converse with, and acquire knowledge from, beings of a superior nature: but I was wretched, helpless, and alone. . . [after discovering and reading Frankenstein's journal, the creature responds] ‘Hateful day when I received life!' I exclaimed in agony.  ‘Accursed creator!  Why did you form a monster so hideous that even you turned from me in disgust?  God, in pity, made man beautiful and alluring, after his own image; but my form is a filthy type of yours, more horrid even from the very resemblance.  Satan had his companions, fellow-devils, to admire and encourage him; but I am solitary and abhorred.'" (Chapter XV)

     * * * * * * * * * * * * Creature:  "‘Cursed, cursed creator!  Why did I live?  Why, in that instant, did I not extinguish the spark of existence which you had so wantonly bestowed?'"  (Opening of Chapter XVI)

Creature: "‘You, who call Frankenstein your friend, seem to have a knowledge of my crimes and his misfortunes.  But in the detail which he gave you of them, he could not sum up the hours and months of misery which I endured, wasted in impotent passions.  For while I destroyed his hopes, I did not satisfy my own desires.  They were for ever ardent and craving; still I desired love and fellowship, and I was still spurned.  Was there no injustice in this?  Am I to be thought the only criminal, when all human kind sinned against me? . . . I, the miserable and the abandoned, am an abortion, to be spurned at, and kicked, and trampled on. . . . ‘But it is true that I am a wretch.  I have murdered the lovely and the helpless; I have strangled the innocent as they slept, and grasped to death his throat who never injured me or any other living thing.  I have devoted my creator, the select specimen of all that is worthy of love and admiration among men, to misery; . . . You hate me, but your abhorrence cannot equal that with which I regard myself.  I look on the hands which executed the deed; I think on the heart in which the imagination of it was conceived, and long for the moment when these hands will meet my eyes, when that imagination will haunt my thoughts no more.'"