"Sin" and its partners "perfection and "imperfection" are religious constructs.They are key parts of the control apparatus to put worshippers under obligations.
They only exist in the minds of believers.There is no way of measuring or quantifying sin, it is a mythical explanation for not being perfect when a perfect mythical god supposedly created humans who supposedly became imperfect.
One of the joys of waking up from this fallacy is the realisation that we are not made imperfect from an ancestor's misdeeds and we do not wear the burdensome cloak of guilt, unless of course we deliberately harm others or break the law. Neither do we need to grovel to an invisible god to get a pardon through human sacrifice.
Religion and its insistence on sin infantilises us putting us back to the helplessness of childhood and dependency on others. Christian religions in effect teach that we are all naughty children.
Was it inevitable? It doesn't exist.