During the October 2026 meeting of our DNA SIG, we discussed the recent revelation of autosomal DNA testing being used to compare clippings of Thomas Jefferson’s hair to that of descendants of Sally Hemings whom Jefferson had enslaved. You can read more at https://www.smithsonianmag.com/smithsonian-institution/did-thomas-jefferson-father-sally-hemings-children-after-more-than-decade-research-answer-finally-firmly-hand-180989331/ or
https://www.biorxiv.org/content/10.64898/2026.09.18.752809v1 or by checking out Richard Kurin’s recent book, History By a Hair.
But this was not the first time DNA was used to answer the question of who was the biological father of Sally Hemings’s children. In the early days of DNA testing, Y-DNA was used to compare known Hemings descendants to known Jefferson descendants.
The National Genealogical Society Quarterly devoted a special issue in 2001 to the testing and the documentary research that backed up the assertion that Thomas Jefferson himself was the father rather than some other family member. They have now made the special issue available to everyone, NGS member or not. See https://www.ngsgenealogy.org/ngsq/jeffersonhemings/ for more information.
We genealogists love evidence and reasonably exhaustive research!