Callender, after being denied a position as postmaster, alleged Jefferson had taken Hemings as a concubine and fathered several children with her. In 1998, a panel of researchers conducted a Y-DNA study of living descendants of Jefferson's uncle, Field, and of a descendant of Hemings's son, Eston Hemings. The results, released in November 1998, showed a match with the male Jefferson line. Subsequently, the Thomas Jefferson Foundation (TJF) formed a nine-member research team of historians to assess the matter. In January 2000 (revised 2011), the TJF report concluded that "the DNA study ... indicates a high probability that Thomas Jefferson fathered Eston Hemings." The TJF also concluded that Jefferson likely fathered all of Hemings's children listed at Monticello. In July 2017, the TJF announced that archeological excavations at Monticello had revealed what they believe to have been Sally Hemings's quarters, adjacent to Jefferson's bedroom. In 2018, the TJF said that it considered the issue "a settled historical matter." Since the results of the DNA tests were made public, the consensus among most historians has been that Jefferson had a sexual relationship with Sally Hemings and that he was the father of her son Eston Hemings. Still, a minority of scholars maintain the evidence is insufficient to prove Jefferson's paternity conclusively. Based on DNA and other evidence, they note the possibility that additional Jefferson males, including his brother Randolph Jefferson and any one of Randolph's four sons, or his cousin, could have fathered Eston Hemings or Sally Hemings's other children. In 2002, historian Merrill Peterson said: "in the absence of direct documentary evidence either proving or refuting the allegation, nothing conclusive can be said about Jefferson's relations with Sally Hemings." Concerning the 1998 DNA study Peterson said: "the results of the DNA testing of Jefferson and Hemings descendants provided support for the idea that Jefferson was the father of at least one of Sally Hemings's children." After Thomas Jefferson's death, although not formally manumitted, Sally Hemings was allowed by Jefferson's daughter Martha to live in Charlottesville as a free woman with her two sons until her death in 1835. The Monticello Association refused to allow Sally Hemings' descendants the right of burial at Monticello. Interests and activities Jefferson was a farmer, obsessed with new crops, soil conditions, garden designs, and scientific agricultural techniques. His main cash crop was tobacco, but its price was usually low and it was rarely profitable. He