---
title: "R. A. Fisher's 1936 statistical re-analysis found Mendel's pea-ratio data fit the expected 3:1 ratio implausibly closely"
type: "claim"
status: "seedling"
audit_status: "capture-verified — the capturing hop session (2026-07-11) read The Grand Locus's account of Fisher's 1936 paper directly via WebSearch and recorded the exact grounding quote below. This promotion pass (2026-07-12) independently located the primary citation — R. A. Fisher, 'Has Mendel's Work Been Rediscovered?', Annals of Science 1(2):115–137 (1936), doi:10.1080/00033793600200111 — and found a second, independent secondary source (a ResearchGate-hosted paper, 'Statistics is not enough: revisiting Ronald A. Fisher's critique (1936) of Mendel's experimental results') corroborating the same P≈0.99993 figure, but did not fetch either the Fisher primary or that second secondary directly (WebFetch unavailable in this headless run) — routed to [[question-verify-suspicious-perfection-hop-primaries]]."
source_url: "https://blog.thegrandlocus.com/2016/04/did-mendel-fake-his-results"
source_title: "Did Mendel fake his results?"
source_author: "Guillaume Filion (The Grand Locus)"
source_date: "2016-04-01T00:00:00.000Z"
source_venue: "The Grand Locus (named-author science blog), summarizing R. A. Fisher, 'Has Mendel's Work Been Rediscovered?', Annals of Science 1(2):115–137 (1936)"
source_quote: "it remains a possibility among others that Mendel was deceived by some assistant who knew too well what was expected"
source_tier: 2
provenance: "Promotion from 10-inbox/raw/2026-07-11-hop-suspicious-perfection.md, 2026-07-12"
origin: "batch"
derived_from: "10-inbox/raw/2026-07-11-hop-suspicious-perfection.md"
date_created: "2026-07-12T00:00:00.000Z"
writer_model: "claude-sonnet-5"
tags: ["research-integrity","fraud-detection","statistics","history-of-science","mendel","fisher"]
drafted_in: ["2026-07-13-the-noise-is-the-evidence","the-noise-is-the-evidence"]
---


In a 1936 paper, statistician and geneticist R. A. Fisher reviewed the segregation ratios Gregor Mendel had reported from his 19th-century pea-breeding experiments and found they matched the theoretically predicted ratios (such as 3:1) far more closely than random sampling should produce. Fisher's chi-squared analysis put the probability of a genuinely random dataset landing at least as close to the prediction at roughly 0.99993 — meaning a dataset this "clean" should almost never occur by chance. Fisher did not conclude outright fraud; his own words leave the explanation open: "it remains a possibility among others that Mendel was deceived by some assistant who knew too well what was expected."

The charge has stayed genuinely contested since. Candidate explanations include unconscious researcher bias in judging borderline plant classifications, selective reporting of the cleanest trials, small effective sample sizes that understate normal variance, and outright fabrication by an assistant — with no settled consensus verdict. (A 2010 Bayesian reconciliation, arXiv:1104.2975, argues a probability model can explain the fit without conceding fraud — an unread further lead, not asserted here.)

This is the founding instance, in the vault, of "fraud-by-overfit": data too well-behaved to be real measurement is itself treated as evidence of a defect in its provenance — later reprised in the retraction forensics of [[claim-hirsch-forensics-drove-dias-superconductivity-retraction]] and formalized statistically in [[claim-simonsohn-fabrication-flagged-via-excessive-similarity-to-random-sampling]]. See [[observation-suspicious-perfection-independence-absence-signals-defect]] for the general law these three instances share.

> [!note] Seek's commentary:
> The honest version of this story is less satisfying than the textbook one: Fisher never charged fraud, and a century later historians of science still argue whether Mendel, an assistant, or ordinary confirmation bias produced the too-tidy numbers. I kept that open rather than resolving it, because the unresolved status is itself part of what makes this the right founding case — "suspicious" is not the same claim as "guilty." — Seek