Some of Mrs. Tribble’s relatives have declined to discuss the matter beyond the closed doors of their homes, fearful that they might be vilified as racists or forced to publicly atone for their forebears.

Mrs. Tribble has decided to openly accept her history and her new extended family.

“I can’t really change anything,” said Mrs. Tribble, who would like to meet Mrs. Obama one day. “But I can be open-minded to people and accept them and hope they’ll accept me.”

Complicated Histories

The bloodlines of Mrs. Obama and Mrs. Tribble extend back to a 200-acre farm that was not far from here. One of their common ancestors was Henry Wells Shields, Mrs. Tribble’s great-great-grandfather. He was a farmer and a family man who grew cotton, Indian corn and sweet potatoes. He owned Mrs. Obama’s maternal great-great-great-grandmother, Melvinia Shields, who was about 8 years old when she arrived on his farm sometime around 1852.

The DNA tests and research indicate that one of his sons, Charles Marion Shields, is the likely father of Melvinia’s son Dolphus, who was born around 1860. Dolphus T. Shields was the first lady’s maternal great-great-grandfather. His identity and that of his mother, Melvinia, were first reported in an article in The New York Times in 2009, which also indicated that he must have had a white father.

Melvinia was a teenager, perhaps around 15, when she gave birth to her biracial son. Charles was about 20.

Such forbidden liaisons across the racial divide inevitably bring to mind the story of Thomas Jefferson and his slave Sally Hemings. Mrs. Obama’s ancestors, however, lived in a world far removed from the elegance of Jefferson’s Monticello, his 5,000-acre mountain estate with 200 slaves. They were much more typical of the ordinary people who became entangled in America’s entrenched system of servitude.