When Ancestry ThruLines Works — and When It Doesn’t

Ancestry ThruLines can be a useful tool for exploring DNA connections, but its effectiveness depends heavily on the underlying tree data.

In my experience, ThruLines is most responsive when there is little or no established consensus—and least useful when incorrect conclusions are widely repeated.

When It Worked

In one case involving Joseph Bishop Sr. (1785–1868) of Campbell County, Georgia, no father had been identified in public trees. DNA matches placed him within a large Bishop family from the Spartanburg District and surrounding areas.

By temporarily testing various candidate fathers in the tree and reviewing the resulting ThruLines output—focusing on shared centimorgans, segment counts, and match clustering—the possibilities narrowed to two brothers within that family.

This approach worked because no competing father had been established, allowing ThruLines to reflect changes in the research tree.

A similar result occurred in a case involving Nancy Lane of Macon County, Alabama, where only a single tree suggested a possible father. With no strong competing narrative, ThruLines generated match patterns consistent with the tested hypothesis. Of the three possible fathers (men named Lane), only one returned many matches among siblings, including twins who were both doctors. That information was not given to me until after I submitted my findings.

When It Did Not Work

In contrast, research involving Keziah McCorkle produced a different result. Although documentary evidence shows that Cornelius McCorkle was married to Prudence, thousands of public trees incorrectly identify him as Keziah’s husband.

ThruLines consistently presented Cornelius as the father of her children, and changes to the research tree had no effect. The volume of incorrect trees appears to reinforce the error.

A similar issue arose in another Bishop project, where multiple individuals—Abner Bishop, his son Allen Bishop, and another Allen Bishop in Alabama—have been conflated across public trees. Many trees assign Allen’s father as William Glover Bishop when it was most likely Abner Bishop.

Despite correcting these relationships, ThruLines continued to present the same lineage, suggesting that widely repeated conclusions can override individual corrections.

A related warning sign appears when the same DNA matches are attached to both an individual and that individual’s spouse. When identical match sets appear under both parties, it often indicates that the relationship is being inferred from widely copied tree data rather than independent evidence. In such cases, the couple itself—or one of the individuals—should be treated as suspect.

Conclusion

These cases suggest that ThruLines is not an independent analytical tool. Its output is shaped by the underlying tree data.

When little consensus exists, it can help evaluate hypotheses. When a strong consensus—correct or incorrect—is present, it may simply reinforce that conclusion.

For that reason, ThruLines is best used as a tool for identifying DNA matches and patterns, not as evidence of a proven relationship.