Population genetics shows humanity descended from a population of thousands, never fewer than about 1,000-10,000 individuals, which rules out a literal Adam and Eve as the sole biological ancestors of the human race — a cornerstone of the Christian doctrine of original sin.

Why people find it persuasive

This isn't a fringe claim; it's the mainstream, well-replicated conclusion of population genetics using multiple independent methods (linkage disequilibrium, allele diversity patterns), and it directly contradicts a straightforward reading of Genesis 2-3 and Paul's argument in Romans 5 that sin entered through 'one man.'

Important distinctions

• • Sole-genetic-progenitor Adam and Eve (no other ancestral population) vs. a real, historical Adam and Eve as genealogical/federal head of a wider population.
• • Literal six-day, ex-nihilo, single-couple creation vs. theologically real historical individuals within an evolutionary process.
• • Original sin as inherited biological genetic defect vs. as inherited corrupted relationship/spiritual condition and representative guilt.
• • Genesis as a scientific population-history document vs. as an ancient theological narrative using historiographic conventions of its genre.

Christian response

• • Population genetics constrains genetic bottleneck size (the 'minimum breeding population' estimate), but this is a different question from whether two individuals, Adam and Eve, could have existed as real historical persons within or alongside a wider hominid population, later singled out and given a unique spiritual/covenantal status — several serious evangelical geneticists and theologians (S. Joshua Swamidass, a computational biologist, in 'The Genealogical Adam and Eve') have shown that a recent, real, individual Adam and Eve are fully compatible with the genetic data if Adam and Eve interbred with a contemporary population, since genealogical ancestry (who you descend from in your family tree) spreads through a population vastly faster than genetic ancestry (which genes you carry) — mathematically, a single couple could become the genealogical ancestor of everyone alive within a few thousand years even while genetic diversity data reflects a much larger ancestral population.
• • This model preserves a real Adam and Eve, a real Fall, and universal human descent from them genealogically (which is what Romans 5 and 1 Corinthians 15's theological argument actually requires — that all humanity is united to Adam in a real, inheritable way, not that Adam was the sole genetic source of every allele in the human genome, a modern population-genetics concept the biblical text was never making claims about one way or the other).
• • Other serious theological approaches (held across a spectrum from young-earth to evolutionary creationism) include reading Genesis 1-3 as a theological account using the literary conventions of ancient Near Eastern origins narratives (comparable to Enuma Elish or the Atrahasis epic in genre, while radically different in theological content) — concerned with covenantal, moral, and vocational truths about humanity's relationship to God, not with modern genetic population history, a category the original audience had no access to and the text shows no interest in addressing.
• • Still others (e.g., some evolutionary creationists like Denis Alexander) locate a real Adam and Eve as a pair God chose out of a wider evolving hominid population and uniquely endowed with the imago Dei and moral responsibility at a particular point in salvation history, whose disobedience then had covenantal consequences for the wider population they represented — analogous to a federal-headship model already present in classical theology (Adam as representative, not merely biological source, closely paralleling how Christ's headship in Romans 5 doesn't require every human to be Christ's biological descendant).
• • None of these harmonizations is forced or ad hoc; they draw on independently motivated resources already present in the theological tradition (federal/covenantal headship, ancient Near Eastern genre analysis) combined with rigorous, published, peer-reviewed population genetics — meaning thoughtful Christians engaging seriously with the science have multiple live, non-desperate options rather than facing a stark forced choice between denying genetics or abandoning the Fall.

Christian counterresponse

It is true these proposals are motivated by theological commitments, but that alone doesn't make them false — all theory-rescuing moves in the history of science and theology are motivated by something, and the relevant question is whether the resulting model is internally coherent, consistent with the data, and not ad hoc in a vicious sense (i.e., does it independently illuminate other things, or only save the one claim). The genealogical-Adam model is a serious, published, technically rigorous piece of population genetics engaged with directly by geneticists, not a theological hand-wave, and ancient Near Eastern genre analysis of Genesis was developed by scholars studying comparative literature on independent grounds, not invented solely to dodge Darwin.