A lock of hair preserved at Monticello has provided new DNA evidence linking Thomas Jefferson to descendants of Sally Hemings, adding weight to the conclusion reached by many historians that the former president fathered children with the woman he enslaved. The research was led by Richard Kurin, a Smithsonian Institution scholar who spent 15 years searching for Jefferson’s genetic material. His investigation is described in his new book, “History by a Hair: Thomas Jefferson, Sally Hemings & Solving a 200-Year-Old Mystery.” A scientific paper detailing the work is under review for publication. The key sample came from a packet held in the collections of the Thomas Jefferson Foundation at Monticello, Jefferson’s plantation and primary residence near Charlottesville, Virginia. The packet was labeled as hair cut from Jefferson on July 4, 1826, the day he died. An earlier search had focused on strands found in Jefferson’s personal Bible, but testing showed those hairs did not belong to him. Researchers later located the larger lock in a packet that had not appeared in the original inventory. Scientists were able to recover and sequence DNA from the sample. Kurin’s team compared that genetic material with descendants of Madison Hemings and Eston Hemings, Sally Hemings’ two youngest surviving sons. The researchers found that those descendants carried substantial amounts of DNA matching Jefferson’s genome—more, Kurin said, than expected based on the known Jefferson family lines. “The DNA speaks for itself,” Kurin said when asked whether the results answered the paternity question. The findings build on DNA testing conducted in the late 1990s by pathologist Eugene Foster and colleagues. That work identified Jefferson-family Y-chromosome markers in a descendant of Eston Hemings, while historical records and family testimony also pointed to Jefferson. Critics noted that the earlier testing could not distinguish Jefferson from another male relative, such as a cousin, brother or nephew. The newly recovered sample is intended to address that limitation by providing DNA directly attributed to Jefferson. Researchers at the University of California, Santa Cruz—including ancient-DNA scientist Beth Shapiro and paleogenomics and forensic-genomics expert Richard “Ed” Green—helped with the project. The history remains inseparable from the power imbalance at its center. Hemings was enslaved by Jefferson and was about 30 years younger than him. Their alleged relationship has therefore been debated not only as a question of genealogy but also through the lens of sexual coercion, consent and the realities of slavery. Jefferson enslaved more than 600 people during his lifetime, many of whom worked at Monticello cultivating tobacco and other crops and maintaining the plantation. He was also the principal author of the Declaration of Independence, including its assertion that “all men are created equal”—a contradiction that has made the Hemings relationship central to debates about his public legacy. Researchers identified descendants of Madison and Eston Hemings but have not found descendants of Hemings’ other surviving children, Harriet and Beverly. The two left Monticello in 1822, lived in Washington, D.C., and passed as white, making their family lines difficult to trace. Kurin hopes to make Jefferson’s genome publicly available. That could allow descendants whose family histories were obscured by slavery and racial passing to investigate possible connections. “This story is not over yet,” he said.