Why DNA Is Only Part of the Story and How it Affects Jewish Genealogy
DNA testing has given genealogy something previous generations of researchers could scarcely have imagined: the ability to identify biological relationships through material inherited directly from our ancestors.
That is an extraordinary evidentiary resource.
It is also very easy to misunderstand.
Popular discussions of genetic genealogy sometimes create the impression that our DNA contains a compressed version of our entire family history, waiting for sufficiently sophisticated technology to decode it. Under this model, documentary genealogy is almost an older and less precise method: archives tell us what people wrote down, while DNA supposedly tells us what really happened.
The relationship is considerably more complicated.
DNA can provide powerful evidence of biological inheritance. It can identify or support relationships, reveal previously unknown branches of a family, challenge an established pedigree and provide clues where documentary research has reached an apparent dead end. Population genetics can also tell us something about the deeper ancestral populations from which portions of our genetic inheritance derive.
But DNA does not contain a family tree.
It does not preserve the names of our ancestors, the languages they spoke, the communities to which they belonged, the countries whose laws governed them, the reasons they migrated, the people they married, the children they raised, the religions they practised or the identities they understood themselves to possess.
Those things belong to history.
Reconstructing a family therefore requires us to distinguish between genetic ancestry and genealogical ancestry.
They overlap.
They are not the same thing.
You did not inherit DNA equally from every ancestor
At the simplest level, autosomal inheritance appears mathematically tidy.
We inherit approximately half of our autosomal DNA from each biological parent. Each parent inherited approximately half from each of their parents. It therefore seems reasonable to imagine inheritance continuing backwards in predictable fractions: approximately 25 per cent from each grandparent, 12.5 per cent from each great-grandparent, and so forth.
As a conceptual model, this is useful.
As a description of what happens to particular ancestral DNA through many generations, it is incomplete.
Autosomal DNA is recombined when eggs and sperm are formed. Chromosomes inherited from a person's parents are broken and reshuffled before being passed to the next generation. The child consequently receives a new combination rather than an exact miniature copy of each grandparent's contribution.
This is why siblings, unless they are identical twins, do not inherit precisely the same DNA from their parents.
They have the same genealogical grandparents.
They have different genetic inheritances from those grandparents.
As this process repeats across generations, some ancestral DNA fragments become smaller and others disappear from a particular descendant's inherited genome altogether.
This leads to one of the most important distinctions in genetic genealogy:
Every genetic ancestor is a genealogical ancestor, but not every genealogical ancestor is necessarily represented by detectable autosomal DNA in a living descendant.
A person can be demonstrably descended from an ancestor and nevertheless possess no identifiable autosomal DNA inherited from that particular individual.
The genealogy remains true.
The genetic signal has simply been lost through inheritance.
Your family tree is larger than your genetic inheritance
The number of genealogical positions in a pedigree expands rapidly as we move backwards.
Two parents.
Four grandparents.
Eight great-grandparents.
Sixteen great-great-grandparents.
In an idealised pedigree without pedigree collapse, the number continues doubling with each generation.
DNA does not expand accordingly.
The genome available to a living individual remains finite, while recombination continually reshuffles the genetic material transmitted through the generations.
Eventually, the number of genealogical ancestors becomes far greater than the number who can have contributed identifiable autosomal segments to the present individual.
This means that a person's genealogy extends beyond the portion of the family represented in their detectable autosomal DNA.
That fact is sometimes surprising because we intuitively treat biological descent and genetic inheritance as synonyms.
They are not.
If documentary evidence establishes that a woman living in the eighteenth century was your ancestor, the absence of an identifiable DNA segment attributable to her does not remove her from your family tree.
You are still descended from her.
You simply may not have inherited detectable autosomal DNA from her.
DNA therefore cannot recover every ancestor
This has a practical consequence.
A person may take an autosomal DNA test hoping eventually to identify every ancestral line.
DNA cannot guarantee that outcome.
Close relationships are generally much easier to detect genetically because substantial amounts of DNA are shared. As genealogical distance increases, however, the amount of shared autosomal DNA generally decreases and the range of possible inheritance becomes wider.
Eventually, genuine genealogical cousins may share no detectable autosomal DNA.
This does not mean that the family tree is wrong.
It means that the genetic inheritance capable of revealing the relationship did not survive in both tested descendants in a detectable form.
For distant genealogy, documentary evidence therefore does something DNA cannot: it can preserve relationships after the biological signal available to a particular living descendant has disappeared.
A seventeenth-century parish or communal register can identify a parent and child even when no living descendant retains DNA which can be attributed specifically to that relationship.
Paper can sometimes remember what the genome no longer contains.
DNA tells us about biological relationships, not necessarily family relationships
There is another distinction which becomes increasingly important as genetic testing enters ordinary family research.
Biology and family are not synonymous.
A person may have a biological father and a different man who raised them as a father.
A child may have been adopted.
A step-parent may have become the only parent the child remembered.
A widowed person may have remarried, and the second spouse may have raised children from the first marriage.
A child might have been fostered informally by relatives.
An orphan might have been raised by an aunt and uncle and subsequently treated socially as their child.
A family might deliberately conceal an illegitimate birth.
None of these relationships is less historically significant because it is not represented by shared DNA.
Genetic testing may reveal the biological relationship.
Genealogy must reconstruct the family.
Those are different tasks.
A purely genetic pedigree could therefore produce an accurate account of biological transmission while simultaneously providing an incomplete account of the family as it was actually lived.
Records can lie, but DNA can be misinterpreted
One of the attractions of DNA is the perception that it is objective.
In an important sense, it is. A DNA sequence is not influenced by whether a nineteenth-century clerk misunderstood a surname or whether a grandfather chose not to discuss his first marriage.
But the interpretation of genetic evidence remains a human analytical process.
A particular amount of shared autosomal DNA can correspond to more than one possible genealogical relationship. Researchers must evaluate ages, generations, family structure and other matches to determine which relationship is plausible.
A DNA match tells us that two people probably share biological ancestry within a certain genealogical range.
It does not automatically identify the common ancestor.
That ancestor must still be found.
The distinction resembles documentary research more closely than is sometimes acknowledged. A record provides evidence which must be interpreted in context. DNA provides evidence which must also be interpreted in context.
Neither becomes a family history merely by existing.
A match is not an ancestor
This distinction is fundamental.
Suppose two individuals share a significant amount of DNA.
The genetic evidence indicates biological relationship.
But through whom?
Perhaps they descend from the same great-grandparents.
Perhaps there are several possible relationships.
Perhaps the families intermarried repeatedly.
Perhaps the apparent relationship is affected by endogamy.
The DNA match identifies a problem to solve.
Genealogical research attempts to solve it.
That process may require constructing the match's family tree, comparing surnames and localities, examining shared matches, identifying migration patterns and locating documentary connections between the two pedigrees.
DNA can therefore be extraordinarily effective at bringing two living people together.
The archive is often what introduces them to the dead person who connects them.
Endogamy makes Jewish genetic genealogy particularly complicated
Jewish genealogy provides an especially important example because many Jewish populations historically practised substantial endogamy: marriage occurred predominantly within the community over many generations.
This does not mean that everyone within an endogamous population is closely related in the ordinary genealogical sense.
It means that ancestral lines repeatedly intersect.
Two Ashkenazi Jews, for example, may share DNA through multiple distant ancestral pathways rather than through one recent common ancestor.
The amount of shared DNA can consequently make a relationship appear genealogically closer than a simple relationship model would suggest.
A match which would be relatively straightforward to interpret in a largely outbred population may therefore require greater caution in an endogamous population.
This is one reason Jewish genetic genealogy cannot simply be approached through a table converting centimorgans into relationships.
The number is evidence.
The population history affects its meaning.
Endogamy also changes what a family tree looks like
The traditional pedigree diagram assumes that every ancestral position contains a different person.
Historical families rarely behave so neatly. Cousins marry. Distant relatives marry.
Branches separate and reconnect. In relatively small or endogamous populations, the same ancestor may occupy several positions within a descendant's pedigree.
This phenomenon, commonly described as pedigree collapse, means that the theoretical number of ancestral positions is larger than the number of unique individuals occupying them.
For Jewish genealogy, particularly in communities which remained relatively small or geographically concentrated for long periods, this can become highly significant.
A DNA match may therefore reflect several overlapping relationships.
Documentary genealogy is required to reconstruct those relationships and determine how the families actually intersect.
The genetic evidence reveals connection.
The historical evidence gives that connection structure.
Autosomal DNA is only one form of genetic evidence
When people speak casually about a genealogy DNA test, they usually mean autosomal DNA. Autosomal testing is enormously useful because it samples inheritance from many branches of the recent family tree, but other forms of DNA follow very different inheritance patterns.
Y-chromosome DNA is transmitted through the direct paternal line from father to son. It can therefore be valuable when investigating a male-line relationship or comparing paternal lineages. Mitochondrial DNA is inherited through the maternal line. Both men and women inherit mitochondrial DNA from their mothers, but only women transmit it to the next generation. It can therefore provide information concerning a direct maternal lineage.
These tests can reach along particular lines in ways autosomal DNA cannot.
Their limitation is precisely the same characteristic.
They represent particular lines.
Your direct paternal line is only one branch of your ancestry.
Your direct maternal line is another.
Hundreds or thousands of other genealogical ancestors may lie between those two lines without being represented by either Y-DNA or mitochondrial DNA.
A haplogroup is therefore not a complete ancestral identity.
It describes one genetic lineage within a vastly larger family history.
Haplogroups are not nationalities
Haplogroups can be fascinating because they connect an individual to very deep patterns of human migration.
They can also be badly overinterpreted.
A Y-DNA or mitochondrial haplogroup may be associated statistically with particular geographical regions or populations. That does not mean that everyone carrying that haplogroup belongs to one ethnicity, nationality, religion or historical community.
Human populations have moved, mixed and divided repeatedly.
Political borders are extremely recent when compared with many genetic lineages.
A haplogroup may therefore be thousands or tens of thousands of years older than the national, religious or cultural identities people attempt to attach to it.
The statement:
My mitochondrial haplogroup is associated with population X
is not equivalent to:
My maternal-line ancestor in 1750 belonged to community X.
The second proposition requires historical evidence.
Genetics can provide context.
It cannot manufacture a documented identity for an ancestor who lived thousands of years after the relevant genetic lineage originated.
Ancestry percentages are models, not ancestral certificates
Consumer ancestry reports introduce another form of genetic information.
Companies compare portions of a customer's DNA with reference populations and estimate which populations the genetic material most closely resembles.
These results can be remarkably informative.
They can identify previously unknown ancestry, support known family origins and distinguish population histories which documentary research alone might never reveal.
But the percentage should be understood for what it is.
It is an estimate produced by comparing genetic data with reference datasets through a particular analytical model.
It is not a census of ancestors.
If a result assigns a particular percentage to an ancestry category, the software has not identified the corresponding number of ancestors and inspected their identities individually.
The population assignment and the genealogical pedigree remain separate analytical objects.
This is why siblings can receive somewhat different ancestry results despite having exactly the same parents.
They inherited different combinations of parental DNA.
Their family history did not change.
Their genetic sample of that history did.
Reference populations are themselves analytical constructions
Ancestry estimates depend upon reference populations.
The testing company needs groups of individuals whose ancestry can be used to characterise genetic patterns associated with particular populations or regions.
Those populations are not necessarily equivalent to modern states.
Human genetic history does not obey contemporary political borders.
Neighbouring populations may be genetically difficult to distinguish because they share substantial historical ancestry. Other populations may be easier to identify because geographic, religious or social isolation produced distinctive patterns over time.
Reference datasets also develop as companies obtain more data and refine their algorithms.
This is why consumer ancestry estimates can change when a company updates its model.
Your DNA has not changed.
The interpretation has.
That distinction should immediately discourage treating an ancestry percentage as though it were an immutable historical fact.
It is a scientific estimate generated using the best comparative framework available to that particular analysis.
DNA cannot tell us what language an ancestor spoke
Consider how much of family history exists outside the genome.
DNA cannot tell us whether a Jewish ancestor spoke Yiddish, Ladino, Judeo-Arabic, Russian, Polish, German, Persian, Georgian or Hebrew.
Population genetics may suggest geographical or demographic origins.
It cannot tell us which language a particular great-grandmother used when speaking to her children.
For that we need records, letters, community history, geography and sometimes family memory.
The same distinction applies to literacy.
DNA cannot tell us whether an ancestor could read Hebrew.
It cannot tell us whether they attended a particular school.
It cannot tell us whether they signed a marriage record themselves or made a mark because they could not write the administrative language.
These facts may appear minor compared with biological ancestry.
Collectively, however, they are what turn a pedigree into a history.
DNA cannot tell us which state governed an ancestor
A genome does not contain political jurisdiction.
An individual born in a town now located in Belarus may have lived under the Russian Empire.
Another ancestor from present-day Ukraine may have lived under Habsburg rule.
A family living in Jerusalem across several generations may have produced Ottoman, British Mandate and Israeli documentation.
None of these political transitions altered the family's DNA at the moment the border changed.
They profoundly altered the family's documentary environment.
Jurisdiction determined which institutions registered births, marriages and deaths. It affected taxation, military service, residence rights, citizenship and migration documentation. It influenced the language in which names appeared and ultimately affected which archives inherited the records.
DNA can tell us that people are biologically connected across those transitions.
Historical genealogy tells us what those transitions meant.
DNA cannot tell us why someone migrated
Population genetics can reveal large-scale historical movement.
Individual genealogy asks a more personal question.
Why did this person leave? Economic opportunity? War? Persecution? Marriage?
Education? Military service? Zionism? Family reunification? Professional advancement?
A pogrom? The Holocaust? A revolution? A job offer?
We cannot extract that answer from a chromosome.
Sometimes the documentary record will tell us.
A passport file may survive.
A ship manifest may establish the journey.
A letter may explain the decision.
A refugee file may document persecution.
A naturalisation application may reconstruct earlier residence.
Sometimes we will never know.
That uncertainty belongs honestly within the family history.
Genetic evidence should not be used to fill a narrative gap merely because the documentary explanation has been lost.
DNA cannot tell us how an ancestor understood their identity
This is particularly important in Jewish genealogy.
Jewish identity can encompass religion, ancestry, peoplehood, culture, language, community membership and family history.
Those dimensions have interacted differently across time and place.
A genetic test cannot tell us whether an ancestor considered themselves religious.
It cannot tell us whether they attended synagogue.
It cannot tell us whether they identified primarily as Jewish, Polish, German, Ottoman, Hungarian, Russian, Moroccan or through some combination which makes little sense when forced into modern categories.
It cannot tell us whether a person converted.
Conversion does not rewrite the genome.
Nor can DNA alone tell us whether an individual was recognised as Jewish by a particular religious or civil institution at a particular historical moment.
These are historical and sometimes legal propositions.
Biological ancestry may contribute to understanding them.
It cannot replace them.
DNA cannot distinguish every kind of historical relationship
A particularly interesting example concerns parenthood.
Genetic evidence can reveal biological parentage.
Historical records may reveal legal parentage.
Family testimony may reveal social parenthood.
Those three identities can belong to different people.
An adopted child may possess no genetic relationship to the parents whose surname they carried, whose religion they practised, whose language they spoke and whose descendants regarded them as a member of the family.
From a purely genetic perspective, the adoptive relationship disappears.
From a genealogical and historical perspective, removing it would falsify the person's life.
A complete family history may therefore need to preserve both structures:
biological descent and lived family relationship.
Neither invalidates the other.
They answer different questions.
DNA can reveal that the documents are wrong
The complementary relationship also works in the opposite direction.
Documents are not infallible.
A birth certificate may identify a legal father who was not the biological father.
An adoption may have been concealed.
A child may have been registered as belonging to a married couple despite different biological parentage.
A family story may have transformed over generations.
A surname may create an assumption of paternal continuity which genetic testing disproves.
DNA can therefore provide evidence that the documentary pedigree does not accurately represent biological inheritance.
This can be genealogically transformative.
But even then, DNA rarely supplies the entire replacement history automatically.
It tells us that the established explanation is incomplete.
Research must then identify the biological family, determine when the divergence occurred and reconstruct the historical circumstances where possible.
The contradiction becomes the beginning of another investigation.
The archive can explain the DNA
This is one of the most productive ways to understand the relationship between genetic and documentary genealogy.
DNA sometimes explains the archive.
The archive sometimes explains the DNA.
Suppose a researcher discovers an unexpected cluster of DNA matches connected to a particular geographical region.
Documentary research may reveal that an ancestor migrated from that region under a different surname.
Or perhaps a previously unknown marriage explains the relationship.
Perhaps a child was born before the parents' recorded marriage.
Perhaps two families lived in the same small community and intermarried repeatedly.
Perhaps a Holocaust survivor reconstructed their identity after the war under a different name.
The genetic evidence identifies a connection which requires explanation.
The historical evidence provides the context capable of explaining it.
Neither source is subordinate to the other.
They are different forms of evidence addressing different dimensions of the same family.
The Holocaust makes genetic genealogy extraordinarily valuable—and extraordinarily delicate
The Holocaust created circumstances in which genetic genealogy can be particularly powerful. Entire families were murdered. Children survived under false identities.
Records were destroyed. Survivors migrated across continents. Names changed.
Families became separated without knowing who had survived. Descendants may possess only fragments of information about their origins.
DNA can reconnect branches which documentary research alone might never have brought together.
A match can reveal a surviving cousin in another country.
Clusters of matches can help reconstruct an unknown biological family.
Genetic ancestry can provide direction where family memory has been completely lost.
This is one of the remarkable contributions of modern genetic genealogy.
But the historical circumstances also require caution.
Jewish endogamy complicates relationship estimation.
Multiple family lines may contribute to the same match.
The absence of a match cannot automatically prove absence of genealogical relationship at sufficient distance.
And the discovery of biological connection does not itself reconstruct what happened to the people involved.
For that we still need history.
Family memory is evidence too—but it must be evaluated
DNA and documents are not the only sources available to genealogy.
Families remember.
They also forget.
They simplify.
They confuse generations.
They protect secrets.
They repeat stories until interpretation becomes tradition.
Oral history therefore requires the same critical approach as other evidence.
A grandmother's statement that the family came from Odessa may be invaluable.
Perhaps she meant the city.
Perhaps she meant the wider region.
Perhaps Odessa was the port from which the family emigrated rather than the ancestral home.
Perhaps the family lived there for one generation after leaving somewhere else.
The story should neither be accepted uncritically nor dismissed because a database initially appears to contradict it.
It becomes another evidentiary proposition to investigate.
Sometimes DNA supports the memory.
Sometimes records clarify it.
Sometimes all three disagree.
That is where genealogy becomes analysis rather than collection.
Photographs, graves and objects preserve things DNA cannot
Family history also survives materially.
A gravestone may preserve a Hebrew patronymic absent from civil documentation.
A photograph may connect relatives who were never named together in surviving records.
An inscription inside a prayer book may preserve a migration route.
A postcard may establish that two branches remained in contact.
A military medal may lead to a service file.
A marriage ring, family Bible, ketubah, passport, notebook or handwritten address may contain the clue which reconnects generations.
None of these sources contains genetic information.
They contain human information.
The strongest family reconstruction frequently emerges from combining sources which were created for entirely different purposes.
Negative DNA evidence must be interpreted carefully
DNA can be compelling when a match appears.
The absence of a match is more complicated.
For close relationships, expected DNA sharing can make non-matching highly significant.
For more distant relationships, recombination means that genuine genealogical relatives may share no detectable autosomal DNA.
The evidentiary significance of a non-match therefore depends upon the relationship being tested.
This distinction is crucial.
A researcher cannot simply state:
They do not share DNA, therefore they are not related.
The expected relationship, type of DNA test, inheritance pathway and statistical likelihood of detectable sharing all matter.
Genetic evidence, like documentary evidence, must be interpreted according to the question being asked.
The oldest available generation can be genetically invaluable
Because DNA is lost through recombination across generations, older living relatives can preserve genetic information which younger descendants did not inherit.
A grandparent may carry ancestral DNA segments which were not transmitted to a particular grandchild.
An elderly aunt may preserve portions of the family's genetic inheritance absent from her nieces and nephews.
Testing an older generation can therefore provide access to ancestral genetic information which will otherwise disappear when that generation is no longer available.
This is one of the few areas of genealogy in which time can permanently remove evidence that no archive can subsequently restore.
Documents may survive for centuries.
An untested person's unique genetic inheritance does not.
That makes thoughtful DNA testing potentially valuable even where there is no immediate genealogical mystery to solve.
Genetic genealogy works best when the question is precise
DNA testing is most powerful when it is used to investigate a defined genealogical problem.
Are these two branches biologically related?
Could this person be the biological father?
Which side of the family produced this cluster of matches?
Does the genetic evidence support the proposed connection between these two documented families?
Which of several candidate families is consistent with the unknown parentage?
These questions allow genetic evidence to be evaluated alongside documentary evidence.
By contrast, the question:
What is my ancestry?
is almost infinitely broad.
DNA can answer part of it.
Genealogy answers another part.
History answers another.
Family memory answers another.
Culture and lived identity add dimensions which none of those methods can fully reconstruct alone.
Genealogy is the reconstruction of people, not percentages
There is something seductive about numerical evidence.
A DNA result provides percentages.
A match provides centimorgans.
A relationship prediction provides probabilities.
Numbers appear more objective than names misspelled in old records or stories remembered imperfectly by relatives.
But a family is not composed of percentages.
It is composed of people.
The objective of genealogy is ultimately to identify those people and reconstruct the relationships through which their lives intersected.
DNA may tell us that two descendants share biological inheritance.
The family tree tells us through whom.
The records tell us when and where those people lived.
Historical geography tells us which state governed them.
Community history tells us the environment in which they existed.
Migration records tell us where they went.
Letters and testimony may tell us why.
No single category of evidence contains the entire story.
DNA and documentary genealogy are strongest together
The most productive approach is therefore not to ask whether DNA is better than traditional genealogy.
That is the wrong comparison.
A birth record and a chromosome are not competing versions of the same source.
They contain different information.
DNA can establish biological facts which no surviving archive could reveal.
Documents can identify ancestors whose DNA is no longer detectable in a particular descendant.
Genetic matches can expose previously unknown family branches.
Historical records can determine how those branches connect.
DNA can challenge an incorrect pedigree.
Documents can explain why the pedigree became incorrect.
Population genetics can illuminate deep ancestral origins.
Genealogy can identify the individuals who carried that history into the recent family.
The evidentiary strength comes from convergence.
DNA is part of your inheritance. It is not the whole of your history.
Genetic genealogy has permanently changed the way family history can be researched.
It deserves neither dismissal nor mythology.
DNA is evidence of biological inheritance.
Sometimes it is the strongest evidence available.
Sometimes it is the evidence which breaks a case open.
Sometimes it tells us that years of documentary assumptions were wrong.
Sometimes it reconnects relatives whom war, migration or persecution separated generations ago.
But DNA cannot tell us everything we inherited from our ancestors because much of inheritance is not genetic.
We inherit names. Languages. Stories. Religions. Citizenships. Traditions. Silences.
Property. Documents. Family relationships. Migration histories. Trauma. Communities.
And sometimes we inherit questions which nobody remaining in the family knows how to answer.
Those things leave different traces.
The work of genealogy is to bring those traces together.
A DNA test can tell us something remarkable about the biological material which travelled through generations and eventually reached us.
It cannot tell us everything about the people who carried it.
For that, we still have to find them.
DNA can reveal who is biologically connected to the story. Genealogy reconstructs the story itself.
Further Reading and References
International Society of Genetic Genealogy (ISOGG) — Autosomal DNA StatisticsA useful technical reference for understanding autosomal inheritance, recombination, expected DNA sharing between relatives, and why increasingly distant genealogical relatives may share little or no detectable autosomal DNA.
23andMe — Understanding Your Ancestry Composition ResultsUseful for understanding what consumer ancestry percentages actually represent. 23andMe explains that its ancestry estimates are produced by comparing inherited DNA against genetically defined reference populations; it also distinguishes these broader ancestry estimates from more recent Country Matches and Genetic Groups.
23andMe — Reference Populations and RegionsParticularly relevant to the distinction made in this article between genetics and modern nationality. 23andMe explicitly notes that genetic populations do not necessarily correspond to political borders and that some neighbouring populations are difficult to distinguish because of shared history and historical population movement.
23andMe — Can 23andMe Identify Jewish Ancestry?A useful companion source for readers interested specifically in Jewish genetic genealogy. It explains the different information provided by autosomal ancestry composition, mitochondrial haplogroups and paternal Y-chromosome haplogroups, while describing these as providing evidence of Jewish ancestry rather than treating genetics as a complete definition of Jewish identity.
FamilyTreeDNA — Jewish Ancestry Frequently Asked QuestionsEspecially useful for the section concerning Jewish endogamy. The resource discusses the high degree of historical interrelatedness within Jewish populations, the complications this creates for interpreting genetic matches, surname changes, and the limitations of small amounts of apparent Jewish genetic ancestry.
FamilyTreeDNA — Genetic Genealogy GlossaryA useful reference for readers unfamiliar with concepts such as endogamy, DNA segments, haplogroups and other terminology encountered in genetic genealogy. Its definition of endogamy specifically includes the various historical sub-populations of the Jewish diaspora among populations in which long-term marriage within the group affected genetic diversity.
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