There are four 'scientific' claims that original sin exists and they are worth noting :-
* The Selfish Gene hypothesis states that "a predominant quality" in a successful surviving gene is "ruthless selfishness." ... "this gene selfishness will usually give rise to selfishness in individual behavior."
* Psychologists who find a "selfish" trait in children from birth, a trait that expresses itself in actions that are "blatantly selfish." [Horreur!]
* Sociologists who claim that "fraud, corruption, ignorance, selfishness, and all the other vices of human nature." One such, Sumner, enumerates "the vices and passions of human nature" as "cupidity, lust, vindictiveness, ambition, and vanity." He finds such human nature to be universal: in all people, in all places and in all stations in society.
* Then there is the psychiatrist Thomas Anthony Harris who observes that "sin, or badness, or evil, or 'human nature', whatever we call the flaw in our species, is apparent in every person." Harris calls this condition "intrinsic badness" or "original sin."
Well, think about the assumption at the root of this. It is that 'being selfish' is a bad thing and 'being self-sacrificing to the community' is a good thing but this does not stand up once you abstract yourself from the pre-set valuations of the Judaeo-Christian West.
On the contrary, a righteous self-centredness is the basis not of 'sin' but of 'virtue' (an older pagan idea). An intelligent self-centredness, however, understands that the self is served better by a well ordered society and by co-operation than it is either by solipsism (which simply results in isolation) or by submitting to the power relations of other selfish individuals who just happen to have seized the commanding heights of culture and society.
The Christian obsession with sin simply cuts the ground from under those who would challenge the order of things by asserting their own rights and being against the claims of those who are in control of the definitions of good and evil. Let us look at the absurd language of these scientists, psychologists, sociologists and psychiatrists - all representatives of the commanding order.
Is not gene 'selfishness' the evolutionary order of things that scientifically cannot be valued as good or bad in itself but simply as a fact on the ground. Evolution has contructed a being that can undertake compassionate and altruistic acts, define itself and do 'good' things because it chooses to do 'good things'. In other words, far from being 'original sin', the 'selfish gene' is the basis for all that is termed 'good' in the world as well as 'bad'. Its existence requires no attempt to derive the good from outside materiality and the evolutionary process.
And that children are 'blatantly selfish'?! Excellent! So they should be. They have to struggle for their existence as the future. They cannot rely on the competence or concentration of 'nice' parents or other kids. They learn by doing and usually learn co-operation and 'goodness' in doing so. We should worry if they were not starting out as selfish little beasts. An unselfish small child is an evolutionary dead-end.
As for our sociologist, he speaks only of the variation in our evolutionary state that includes examples of all these things that are apparently 'bad' but also examples of everything that is apparently 'good'. There is no flaw in our species that is not a flaw in materiality itself. That materiality is flawed is the most absurd of essentialist propositions once you have eliminated the magical thinking of absolute idealism. The whole language of flaws is sloppy thinking, an external imaginative imposition on the complexity of material reality.
What we see is not original sin against which we must struggle to create some idealistic perfection but a complex and fluid evolutionary reality with maximum variation in which we all have to struggle and live. It contains neither good nor evil in itself or better, given our human perspective, contains all forms of good and evil now and in the future.
This is not 'sin' unless all reality is 'sin. While it is perfectly permissible to take that Gnostic line, any analysis that sees reality and materiality as merely 'sin-based' and our magical thinking as somehow redemption from 'sin' is sending us way up the garden path of anxiety-driven and cowardly evasion.
We are not intrinsically bad or intrinsically good. The desperation in certain personality types to define our species in these terms speaks more to personal neuroses and fears than it does to our reality. The point is that bad things happen to good people and good things happen to bad people not because of original sin but because we are disordered and have not ordered ourselves internally and externally.We have not progressed rather than that we have 'fallen'.
Instead of understanding our nature and creating systems of order that are based on diminishing harms from a close observation of 'what works' (a technology of living in the world), we think that the exhortations of the propertied and powerful on the frightened will somehow change reality itself into something better. When it does not do this, we whine and moan that it is all 'not fair' instead of doing something about it or recognising an occasional truth - that we cannot do anything about it. It is not good or evil but just life. We alone are responsible for our own failures in managing the technology of power to protect ourselves and those we care about. And protecting ourselves and those we love is not 'original sin' but who and what we are.
So, away with this talk of 'original sin' and the attempt to find 'scientific proofs' for our intrinsic 'badness' or 'goodness'. We are neither. We are what we are. In general, it is best for us to do what we will as a balanced self-centredness and harm no one because we have no need to do so. The bulk of us can then organise ourselves to deal with those whose nature is to do harm and perhaps, equally usefully, restrain those who are under the illusion that it is their task, because of their nature, to go around doing unwanted 'good'.
 The original citations for these views are at https://en.wikipedia.org/wiki/Human_nature