How Forensic Genealogists Think

The name matches.

The father's name matches.

The approximate age matches.

The geography makes sense.

Have we found the right person?

Perhaps.

A forensic genealogist's job is to find out why we might be wrong.

Finding a person is only the beginning

Much of genealogy is associated with searching: finding a birth certificate, locating a marriage record, discovering a passenger list or identifying someone in a census.

Forensic genealogy certainly involves searching, but finding a document is only part of the work.

The more important question is:

What does this document actually prove?

A record containing the right name may look promising. But how common was that name? Does the age correspond? Are the parents correct? Does the person's occupation make sense? Can the geography be reconciled? Does the chronology work?

And perhaps most importantly:

What other evidence would have to be true if this really were the person we are looking for?

That is where forensic genealogy begins to differ from simply finding records.

We are not collecting documents that support a story.

We are testing whether the story can survive the documents.

A plausible answer is not necessarily the correct answer

One of the greatest dangers in genealogical research is finding a promising candidate too early.

The first few details align beautifully.

The name is right.

The year is approximately right.

The person appears in roughly the right place.

Suddenly, every new record is viewed through the assumption that the identity has already been established.

A discrepancy in the year of birth? Perhaps an administrative error.

A slightly different surname? Probably transliteration.

A different place of birth? Perhaps the person named the nearest large town instead of the village.

A different first name? Possibly a Hebrew name, a secular name, a nickname or a later name change.

And the difficulty is that every one of those explanations may be perfectly reasonable.

People did change their names.

Officials did make mistakes.

Borders moved.

Languages changed.

Names were transliterated between alphabets.

Migrants sometimes altered their ages.

Records were lost, recreated and incorrectly copied.

The problem arises when we become so invested in an identification that every contradiction receives an explanation while every similarity is treated as proof.

At some point, we have to ask a different question:

How many explanations does this identification require before the simpler explanation is that we have found the wrong person?

Similarities begin a search. They do not end it.

In forensic genealogy, matching information creates a hypothesis.

It does not automatically establish an identity.

Suppose we are looking for a man named Moshe Cohen, born around 1900 in Poland.

We find a Moshe Cohen of approximately the correct age living in another country.

That is interesting.

If his father's name also matches, it becomes more interesting.

If his place of origin corresponds, we may have a strong candidate.

But we still have a candidate.

Now we have to reconstruct his life.

Who did he marry?

Where did he live?

When did he migrate?

Who were his parents?

Did he have siblings?

Where was he when particular events occurred?

Can the person documented in Poland and the person documented abroad exist within the same chronological life?

This last question is particularly important.

Two documents may contain remarkably similar identifying information and still belong to different people.

Conversely, two documents containing apparently different information may ultimately relate to the same person.

The task is not to count similarities and discrepancies.

The task is to understand their evidential weight.

Not all discrepancies are equal

A difference in spelling is not necessarily significant.

A surname written in Polish, Russian, German, Yiddish and Hebrew may appear in several different forms while referring to exactly the same family.

A difference of one or two years in a reported age may also have limited significance, depending on the period and the type of record.

But other contradictions carry considerably more weight.

If two records give completely different parents, we need to understand why.

If the same person appears to be living in two countries at the same time, we need evidence that explains the chronology.

If our candidate appears to have married one person in one country and another person elsewhere, we cannot simply assume that both records belong to him. We need to determine whether the first marriage ended, whether migration between the two locations was possible and whether the rest of the documentary evidence supports that reconstruction.

The question is therefore rarely:

Do these records match?

It is:

Can all of these records reasonably describe one human life?

We look for evidence that proves us wrong

This may be one of the less intuitive aspects of forensic genealogy.

Once I develop a promising hypothesis, I do not only search for evidence that confirms it.

I also look for evidence that could destroy it.

If I believe that a person found in Israel is the same person documented decades earlier in Poland, I want to know what records exist in both countries.

If I believe that two versions of a surname belong to the same family, I want to know whether another family using the same variations existed in the same area.

If I believe that someone emigrated, I want to know whether they continued appearing in records in their supposed country of origin after the alleged migration.

A strong hypothesis should become stronger when challenged.

If it collapses as soon as contradictory evidence appears, it was never a strong identification.

This is why negative findings and contradictions are not failures of research.

Sometimes they are the most valuable results we find.

Every document has a job

A document should not be asked to prove more than it actually can.

A death certificate may tell us when and where someone died. Depending on who provided the information, its details about the deceased's parents or birthplace may be less reliable.

A birth record is usually much closer to the event it documents, but even an original record can contain errors.

A gravestone may preserve a Hebrew name and the name of a father, while telling us very little about the person's civil identity.

A family tree may provide excellent clues, but a clue is not the same thing as independently verified evidence.

An official record may carry significant evidential weight, but the information it contains still needs to be understood in context.

Forensic genealogists therefore constantly ask:

Who created this record?

When was it created?

Who supplied the information?

How close was that person to the event being documented?

Is this an original source or a later transcription?

Could the information have been copied from an earlier error?

Does another independent source confirm it?

The fact that something appears in a document does not automatically make it true.

But it does make it evidence that needs to be evaluated.

Sometimes the answer is no

There is an understandable expectation that genealogical research should end with a discovery.

We found the heir.

We found the missing relative.

We identified the person.

Sometimes it does.

But sometimes the most important conclusion a forensic genealogist can reach is:

No.

No, these are not the same people.

No, this document does not prove the claimed relationship.

No, the person who appears to be the obvious candidate cannot be reconciled with the rest of the evidence.

That conclusion may take considerably more work than finding a plausible match.

It requires us to reconstruct competing identities, examine contradictory records and understand why an earlier identification may have appeared convincing.

Proving that something does not fit can be just as important as proving that it does.

Particularly when the outcome affects an estate, an inheritance, a legal proceeding or the identification of an heir.

The goal is not to be right

When I begin a forensic genealogical investigation, I usually have hypotheses.

Some are strong.

Some are speculative.

Some survive.

Others disappear within an hour.

The purpose of the research is not to defend the first hypothesis.

It is not even to prove my own hypothesis correct.

The purpose is to determine which explanation is best supported by the available evidence.

That requires curiosity, but also scepticism.

It requires imagination to understand how a life might have unfolded across countries, languages and historical upheavals—and discipline to recognise when the documents tell us that it did not unfold that way.

Perhaps the simplest way to describe how forensic genealogists think is this:

We do not ask only whether the evidence supports our theory.

We ask whether the theory can survive all of the evidence.