A new discipline that emerged in the year 2000 thanks to the democratisation of genetic testing, genetic genealogy incites interest, fascination, and sometimes anxiety and controversy. What does it have to do with classical genealogy? How is it organised? What exactly is genetic genealogy? Here is a definition:

How is genetic genealogy practiced?

A genetic test carried out in a genetic genealogy laboratory forms the basis of this discipline. Several different tests are available, the most common being the autosomal test. This test can be used to determine ethnic origins but also to identify common ancestors, shared with genetic cousins, as far back as eight previous generations.

Analysis of the Y chromosome, present only in men, allows us to identify a male family lineage, going back to archaeological times.

The mitochondrial test, present in men and women, can also identify an archaeological ancestor.

Depending on the laboratory's commercial offers, certain tests may be combined.

The genetic genealogy laboratory allows us to carry out one/several tests, but above gives us access to a database of other people who have been tested who share segments of DNA (called matches) with us, therefore our genetic cousins with one or more common ancestors.

The 4 main laboratories are, in order of seniority from the oldest to the most recent: FamilyTree DNA, Ancestry DNA, 23andMe and MyHeritage.

Classical genealogy and genetic genealogy

Classical genealogy is based on civil status certificates or religious registers. In order to complete this research, solicitor's archives can be consulted, but also any official or unofficial documents, any written traces which allow us to map out the life of our ancestors, from judicial archives to land registries of properties. A genealogist soon becomes a local historian, a historian of the daily life of his ancestors.

For my part, I call classical genealogy declarative genealogy, as opposed to genetic genealogy which enables us to determine all biological cousins (within the temporal limits evoked) beyond our borders.

Carrying out a genetic test will allow you to confirm, supplement or disprove all or part of a family tree.

Confirming the family tree

By identifying genetic matches as genealogical cousins, the genetic genealogist will confirm the discoveries of the classical genealogist.

Completing the family tree

Again, by identifying genetic matches the genealogist will be able to find "lost" genetic genealogical cousins, notably:

  • identify one/several undeclared natural father(s) from their genealogy.
  • find unknown genealogical descendants (immigration of an ancestor to France or abroad, unknown remarriage, unknown child of an ancestor, etc).
  • identify an ancestor with certainty (cases of namesakes, ancestors with pseudonyms, change of identity of a French or foreign ancestor, etc).
  • identify the biological family (father and/or mother) of babies born anonymously, born through sperm donation or adopted.

Disproving the family tree

Generally the subject of recurring fantasies, non-filiative events such as a child born of adultery represent an average of 1% in genealogies. They can also concern hidden adoptions, a child resulting from an adulterous relationship, a child with no biological link to a parent, a child resulting from rape or wartime rape, but also mistakenly swapped babies, as this American discovered through a genetic test.

Our Canadian friends, having launched a large study in 2000 involving more than 8,500 descendants of French couples, have estimated these non-filiative events to be 0.5%.

If this percentage is minimal, the risk of a non-filiative event increases over generations. For example, it is estimated that in the previous six generations, there is a 40% risk that one of your 64 ancestors is not your actual biological ancestor, this includes both women and men.

The genetic genealogist

The promises made by genetic genealogy laboratories are often staggering: through genetic testing, your family tree will "build" itself, partly thanks to your DNA matches, but also and above all thanks to the family trees put online by your genetic cousins.

This service allowing you to complete your family tree from other trees is also available for the "classic" genealogist, assuming that coming up with a pile of names and dates of birth, marriage and death is considered genealogical work. For any experienced, serious and passionate genealogist, this would not be enough.

The laboratories' commercial promise has created the fantasy of an independent discipline called genetic genealogy.

However, genetic genealogy is complementary to, and inseparable from, declarative genealogy. It uses classical genealogy to confirm, or not, the data found.

A genetic genealogist, without a family tree of matches, can do and find nothing!

Many people who have been tested have little or no knowledge of their ancestry, so it may be that you have to construct the family tree of your genetic match in order to identify the common ancestor.

Genetic genealogy is also time-limited as the autosomal test can only identify, at best, the previous eight generations (more in the case of endogamy).

This is why I have titled my book DNA, a Genealogical Tool. The genetic genealogist is above all a genealogist who has acquired an additional specialty, genetic genealogy.

The genetic genealogist's missions:

This discipline requires a mastery of genealogy, basic notions of genetics, the various commercial offerings and tools which exist on the internet (as they evolve, disappear or as new tools appear), and a basic understanding of Excel.

To advise

A genetic genealogist must clearly identify the research needs of their "client" in order to advise them which genetic test(s) is/are the most appropriate according to the laboratories' commercial offers, as well as, eventually, other members of their family. A good knowledge of the different genetic genealogy laboratories as well as their fields of activity is necessary.

They must provide information about ethical aspects and ensure that their client's data is protected by foreign laboratories.

To carry out research

Delegated by their client, a genetic genealogist performs the task of identifying common ancestors with the genetic and therefore ethnic matches from their lineage, or part of it.

The genealogist will be able to create one or more surname groups and manage them for their client.

A mastery of the various genetic genealogy laboratory tools available, as well as tools external to them, is essential.

Although rare, requests may relate to very distant ancestry about which a genetic genealogist should be able to inform their client.

To educate

They must put the results obtained in context, particularly ethnicity results.

To monitor technology and document information

In order to offer the best service to their clients, a genetic genealogist must document a significant amount of information corresponding to each of their clients, as the discipline is permanently evolving.

Genetic genealogists specialising in genetics

I hope this article will have enlightened you on genetic genealogy. As always, I count on my well-informed readers to supplement this article with their thoughts and suggestions. This definition of a genetic genealogist is not exhaustive but presents the essential elements of this new specialisation.