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Friday, April 19, 2019

Viewpoint: No, the DNA testing is inconclusive and, at best, proves only that any of Thomas Jefferson's male relatives could have fathered a child with Sally Hemings.


Sally Hemings' last child, born in 1808, was named Eston. That Thomas Jefferson was also Eston's father has been rumored for almost two centuries. According to some historians, Eston bore a close resemblance to President Jefferson and easily entered white society in Madison, Wisconsin, as Eston Hemings Jefferson. These accounts have served over centuries as anecdotal "proof" that Thomas Jefferson was Eston's father.

There has also been a counter-tradition that either Peter or Samuel Carr, the sons of Jefferson's sister, could have been Eston's father.

The Search for an Answer:
In the 200 years since Jefferson's time, science has developed ways of looking at deoxyribonucleic acid (DNA) a molecule often called the messenger of life, to discover the genetic "fingerprints" of inheritance. Recently, some scientists felt that advances in DNA testing could either establish Jefferson's paternity or exonerate him once and for all in the case of Sally Hemings's son, Eston.

In 1998, retired pathologist Eugene A. Foster and colleagues attempted to prove or disprove paternity in the Jefferson-Hemings debate by examining the XY chromosomes in the known male descendants of Thomas Jefferson, the Carrs, and others. To help with the effort, Foster enlisted Jefferson genealogist Herbert Barger, who helped identify Jefferson male descendants who were appropriate for testing.

Testing required identifying that part of the study participants' DNA that would reveal the configuration of their Y chromosome. Every male has two inherited sex chromosomes, the X chromosome from his mother and the Y chromosome from his father. The Y chromosome is passed unchanged from father to son. In their genetic study, Foster and his colleagues found that the Y chromosome in the Jefferson line was quite distinctive. Had it been common, conclusions would have been beyond reach and the Carrs, for example, could not have been excluded as candidates.

Their methodology contained a flaw, however. In testing living Jefferson descendants, they could not exclude from the data genetic traces of long-deceased male members of the Jefferson family, of whom there were many. All, including President Jefferson, could have passed along their Y chromosome to men in the subsequent generations.

The Published Findings:
Study results were published in the British journal Nature on November 5, 1998, under the headline "Jefferson Fathered Slave's Last Child." As the story reappeared in other popular media, the study results became simplified so as to suggest that it was an unequivocal fact that Jefferson fathered a child with Hemings. The study data, however, do not point to this conclusion.

According to Foster: "We … analysed DNA from the Y chromosomes of: five male-line descendants of two sons of the president's paternal uncle, Field Jefferson; five male-line descendants of two sons of Thomas Woodson; one male-line descendant of Eston Hemings Jefferson; and three male line descendants of three sons of John Carr, grandfather of Samuel and Peter Carr. No Y-chromosome data were available from male-line descendants of President Thomas Jefferson because he had no surviving sons."

Foster and his colleagues found that the descendants of Eston Hemings Jefferson did have the Jefferson haplotype. "This haplotype is rare in the population, where the average frequency of a microsatellite haplotype is about 1.5 percent," wrote Foster. "Indeed, it has never been observed outside of the Jefferson family."

Thus, the findings of Foster and his colleagues suggest that Thomas Jefferson could have been Eston's father. At the same time, Foster confirmed that the Carr family haplotypes "differed markedly" from those of the descendants of Jefferson. This finding makes it certain that neither Samuel nor Peter Carr fathered Eston.

However, Foster and his colleagues noted that they could not "completely rule out other explanations of our findings" based in "various lines of descent."

They concluded that "a male-line descendant of Field Jefferson could possibly have illegitimately fathered an ancestor of the presumed male-line descendant of Eston. But in the absence of historical evidence to support such possibilities, we consider them to be unlikely."

The Evidence Falls Short:
In response to the question of paternity, the answer is no, DNA testing has not proven that Thomas Jefferson had at least one child with Hemings.

The data merely suggest that a number of males related to Thomas Jefferson could have fathered Eston. In other words, Jefferson was not the sole guardian of his genetic makeup; the XY chromosome is a DNA "family fingerprint" shared by some of his male relatives, any one of whom could have been the father of Hemings's son, Eston, or later fathered male descendants of Eston.

Because only living persons were tested, the Jefferson XY chromosome could have entered the lineage from several of Thomas Jefferson's contemporary male relatives or at any point in the almost 200 years since the rumor started.

Soon after the Foster article was published, Nature received letters, from scientists as well as nonprofessionals, disagreeing with the study results and, especially, disagreeing with the way they were reported.

In a letter to Nature that appeared in the January 1999 issue, David M. Abbey, MD, chief of medicine at Poudre Valley Hospital, Fort Collins, Colorado, and associate clinical professor of medicine at the Health Sciences Center at the University of Colorado, responded to the Foster study. "The DNA analysis of Y chromosome haplotypes used by Foster, et al to evaluate Thomas Jefferson's alleged paternity of Eston Hemings Jefferson is impressive," wrote Abbey. "However, the authors did not consider all the data at hand in interpreting their results. No mention was made of Jefferson's brother Randolph (1757-1815) or of his five sons. Sons of Sally Hemings conceived by Randolph (or by one of his sons) would produce a Y chromosome analysis identical to that described by Foster, et al." Abbey recommended that more data are needed to confirm Thomas Jefferson's paternity.

Could Jefferson's younger brother, Randolph, be considered an equal (if not better) candidate for being Eston's father? According to historian Eyler Robert Coates, records show that Randolph Jefferson was invited to Monticello in August 1807, about nine months before Eston was born in May 1808. Coates adds that Randolph had become a widower in 1806 and did not remarry until 1809; Coates speculates that Randolph was more likely in this period to be "susceptible to a sexual liaison." Of course, speculation over whether Randolph Jefferson, rather than Thomas Jefferson, was Eston's father is not a fact verifiable by science. He, like some other Jefferson males, was simply in the right place at the right time bearing the family XY chromosome.

Gary Davis, another letter correspondent, added in a letter to Nature (January 7, 1999), that "any male ancestor in Thomas Jefferson's line, black or white, could have fathered Eston Hemings. Plantations were inbred communities," wrote Davis, "and mixing of racial types was probably common .. . it is possible that Thomas Jefferson's father, grandfather or paternal uncles fathered a male slave whose line later impregnated another slave, in this case, Sally Hemings. Sally herself was a light mulatto, known even at this time to be Thomas Jefferson's wife's half sister."

Willard Randall, author of Thomas Jefferson: A Life and member of the God and Country Foundation, a group that seeks to safeguard the reputations of the founding fathers, said that at the time in question there were "20 to 25 men within 25 miles of Monticello who were all Jeffersons and had the same Y chromosome. Of them, 23 were younger than 65 year old Jefferson."

Shortcomings Are Acknowledged:
Even the study's lead author, Foster, admits the evidence is not in any way conclusive about Thomas Jefferson's alleged relationship to Eston. After the controversy over his findings erupted, Foster said in a response letter to Nature (January 7, 1999): "It is true that men of Randolph Jefferson's family could have fathered Sally Hemings later children … . we know from the historical data and the DNA data that Thomas Jefferson can neither be definitely excluded nor solely implicated in the paternity of illegitimate children with his slave Sally Hemings."

As Abbey added, "a critical issue always facing science is confounding variables. It is the scientific standard to comment on such variables when presenting a study, and especially to note how such variables could impact results. It is surprising that the authors (in their original paper) did not even address other conclusions. Too, when the public is presented with authors disagreeing with the title of their own paper, and the press reports conflicting accounts as to the validity of the results, public confidence in the scientific process may be eroded and create unnecessary skepticism toward DNA research in general."

As reported in an article in the Washington Post (January 6, 1999), editors at Nature admitted that the headline was "unintentionally misleading" and confessed as well that more "alternative explanations" should have been included in their conclusions.

Foster was quick to point out the inconsistencies between the data, the conclusions, and the headline. In a follow-up letter in response to letters from Abbey and Davis, he reminded readers of their original objective: "When we embarked on this study, we knew the results could not be conclusive, but we hoped to obtain some objective data that would tilt the weight of evidence in one direction or another."

According to Jefferson historian and genealogist Barger, the evidence for Jefferson's paternity is not tilted in any direction by the data. In conclusion, the DNA XY chromosome testing shows only that Thomas Jefferson could have fathered Eston, but so could any of several of his male relatives. The science is inconclusive, putting the speculation about Jefferson and Hemings back into the category of salacious gossip.