Summary
A bioRxiv preprint reports that DNA recovered from museum hair samples attributed to Thomas Jefferson supports his direct paternity of children descended from Sally Hemings. The study compares inherited DNA shared with known and putative descendants and remains a preprint.
A bioRxiv preprint reports new DNA evidence supporting the long-contested conclusion that Thomas Jefferson fathered children with Sally Hemings, an enslaved woman at Monticello. The researchers recovered DNA from multiple rootless hair samples in a museum collection and compared it with DNA from known and putative descendants of Jefferson.
The study found Jefferson ancestry among descendants connected to both his wife, Martha Wayles Jefferson, and Sally Hemings. When the researchers measured the amount of DNA shared between Jefferson and the descendant groups, the results were more likely under a model of direct Jefferson paternity than under other proposed explanations.
The paper was posted on September 21, 2026, as a bioRxiv preprint. Its conclusions are therefore presented before peer review.
How the historical DNA comparison worked
The central technical challenge was obtaining usable genetic material from Thomas Jefferson himself. The hair samples were rootless, meaning they lacked the follicle tissue that is often the most accessible source of DNA. The researchers say they developed a technique to recover DNA from multiple such hairs.
Several lines of evidence were used to associate the samples with Jefferson. Their provenance, mitochondrial genomes, Y-chromosome markers and identity to one another were consistent with the hairs—and the DNA recovered from them—coming from Jefferson, according to the preprint’s abstract.
The team then examined DNA shared between the Jefferson samples and descendants from the two relevant family lines. This included known descendants of Martha Wayles Jefferson and putative descendants of Sally Hemings. The comparison focused on identical-by-descent DNA: genetic material inherited from a common ancestor. The researchers assessed which historical family scenario best fit the amount of shared Jefferson DNA.
The direct-paternity model produced the stronger fit in the reported comparison. That approach goes beyond earlier analysis of Y-chromosome markers from living members of the Jefferson and Hemings patrilines. Those earlier results were consistent with the paternity hypothesis, but they could not by themselves distinguish Thomas Jefferson from another male in the Jefferson family who might have fathered Sally Hemings’s children.
Why the result matters
The long-running historical dispute involved competing denials and affirmations by family members, biographers and historians. The earlier genetic evidence narrowed the question but left the identity of the relevant Jefferson male unresolved. DNA attributed directly to Jefferson provides the comparison needed to test that specific question more closely.
The preprint’s contribution is therefore both historical and methodological. It combines museum hair samples with genetic genealogy and a model-based comparison of inherited DNA. The result supports a direct connection between Jefferson and descendants of Sally Hemings, while also demonstrating how genetic material from rootless historical hair can be used in lineage analysis.
The inference depends on the identification and provenance of the hair samples, as well as the descendant comparisons and the models used to evaluate alternative family scenarios. The supplied abstract does not report sample counts, numerical likelihoods or the detailed statistical methods. The authors also disclose competing interests, including consulting, employment and an executive role at outside organisations. Further assessment will depend on the full methods and peer review of the preprint.