Genealogical research has traditionally been based on documents: church and civil registers, censuses, probate records, obituaries, old letters, and other archival sources. From these, researchers attempt to reconstruct who is related to whom — as a child, sibling, or more distant relative.However, DNA testing has created a fundamentally new dimension. A historical document shows what was recorded at a particular time about a person’s family relationships. DNA, on the other hand, can provide evidence of a biological relationship. And the two are not always the same.

An incorrect entry in a birth or church register, a name change, adoption, a child born outside marriage, or simply a previously unknown family connection can remain hidden in the records for decades or even centuries. Relevant DNA matches, however, may reveal family connections that could never have been discovered through traditional sources alone. It is important to remember that a DNA match alone does not provide a complete family tree. Depending on the amount of shared DNA, there are usually several possible relationships. Therefore, one of the most exciting aspects of modern genealogical research is combining these two forms of evidence: We interpret genetic matches together with documents, family trees, and other DNA matches.

This can be particularly significant in heir research. When an unknown or uncertain line of descent needs to be investigated, DNA can provide a new direction for research or help evaluate a suspected biological relationship. But here too, an important distinction must be made: Genetic kinship and legally established kinship are not necessarily the same. Even if a DNA test strongly supports a biological relationship, this does not automatically mean that the person is an heir in the legal sense. In inheritance matters, the laws of the relevant jurisdiction determine what evidence can be accepted and what must be proven in the proceedings.

DNA research and its results therefore do not replace civil registers and archival research; rather, they add a new layer of evidence. Perhaps this is what is changing our profession the most. Today, we can ask not only: “What do the documents say?” but also: “Is the genetic evidence consistent with them?”