Claims that Jefferson fathered Sally Hemings's children have been debated since 1802. That year James T. 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 Heming's children listed at Monticello.