The Jefferson-Hemmings DNA study, published in 1998, was one of the catalysts of what later became the field of Genetic Genealogy.
Did Thomas Jefferson father a child with his slave Sally Hemmings?
While DNA cannot prove that Sally Hemmings' child was Thomas' son, Y-DNA did prove that the child's father was "a Jefferson." FamilyTreeDNA has the Y-DNA signature of the Jefferson line:

A simple Y-DNA test can determine whether you match the Jefferson Y-DNA signature and whether you are closely or distantly related.
You can test your Y-DNA to determine whether it matches the Jefferson or any other Y-DNA signature.
DNA testing can show:
- if two people are related
- your suggested geographic origins
- if you match the Jefferson DNA
- your deep paternal ancestral origins
Which Test to Take
Y-DNA Tests (Paternal Line Test) - Click here to learn more and order.
Genetic males can test their Y-DNA to determine the origin of their paternal line. Note that the Y-DNA test strictly checks the paternal line, with no influence from any females along that line. Females do not receive Y-DNA, and therefore females cannot be tested for the paternal line. If you are a female and would like to know about your paternal line, you would need to have a brother or a male relative from that line tested.