The Basics for Solving Unknown Parentage Cases using DNA


Why does testing your DNA help?

You get half your DNA from each parent, about a quarter from each grandparent and so forth if enough biological relatives are tested you can figure this out

You can see from this chart that you will share alot of DNA with your closer relatives but beyond 2nd cousins there is less and less

Chart from the ISOGG wiki  (courtesy Dimario, Wikimedia Commons)

The "G" trick

The cousin level = the number of "G"s for the shared ancestor.

If you are in different generations take the shorter path and the other is removed by the generation difference

Step 1: TEST your DNA:

at Ancestry and 23andme then transfer to the other sites

also test any close biological relatives that will help

Step 2: Upload the Ancestry DNA results to other sites for free to get more matches:

  • MyHeritage*
  • Family Tree DNA *
  • GEDmatch
  • LivingDNA (primarily British, not many matches yet)
  •* (French)

*  pay a little $ to unlock tools

If your roots are deeply American, you may only need to test at Ancestry

Any of these matches may resolve the case quickly for you but proceed carefully

Enter the cMs and get probable relationships

This online calculator that gives you the probable relationships is an invaluable aid


The DNA Adoption web site has much help.They recommend that with very close matches, save all the information you can see before you initiate contact ... review the advice here:

With less close DNA matches, the basic methodology to resolve unknown parentage involves analyzing and building the trees of your best matches ...

Look through the family trees of 2nd, 3rd, and 4th cousin DNA matches for common ancestral couples ("pedigree triangulation")

Use to build private, unsearchable family trees down from each common couple to find where they intersect and produce someone in the right place at the right time.

This may only get to the grandparents  or great grandparents

Once you have a candidate parent build their pedigree tree back to at least 1800

Make sure this tree is private and unsearchable initially but once you are ready to try it out, you make it searchable so that ThruLines can use it for you

Add a fake child to that parent and then connect your DNA to that fake person

Ancestry will use auto complete in the name field

Select the pedigree tree you created and link your DNA test to the fake child

Now wait ... it often only takes a day or two to get common ancestor hints ... see if they are consistent with your hypothesis

Click on each Common ancestor in your match page to view the relationship. Consistent with your theory?

Check the cMs of each match and compare them to the charts

Do they fit your theory?

Clicking on a person's name in the list of matches  takes you to the DNA match page

Does this fit your theory?

Next click on the shared ancestor's name in the left hand column box called "Common Ancestors" to get to this view which shows the relationship

You might try using the "What Are The Odds" tool at DNApainter to check your theory - 

If you can make a GEDCOM of the descendants of the common ancestors, you can upload that to WATO … 

An unknown father case named B had a 779 cM match to a person  some 35 years younger and also a 324 cM match to the daughter of the match

normally that might be enough if the match responds and helps but no such luck

So we checked the possibilities at my favorite online calculator

There were many many more 2nd-3rd cousin level matches descending from his paternal great great grandfather

So we used WATO to combine the chances

We also tried the new relationship calculator at GEDmatch to see if it shed any more light on this

the match did have a small but adequate tree

To combine the probabilities of all the DNA matches to descendants of Caleb Browning b 1832 we made this WATO tree

N.B. The father of the good match is the same age as our B

Underneath the diagram, the possibilities are explained in more detail.

It is 9 times more likely that Son A is the unknown father than those two of his brothers who were in the right place at the right time also ...

So the next step is to get descendants of each possible other brother to test

Let's look at a search that was done for an actual solved case.


Tessa was looking for her unknown father. All she knew his surname was Padilla and that it was an encounter in a town in California in a specific year

23andme match

It's very helpful when one parent or a half sibling is tested

Her Mom


Because you can separate out the matches and ethnicity of the unknown parent

What does this ethnic mix tell us?

Hispanic, Mexico or New Mexico

People with endogamous roots do best to wait for close matches, 2nd cousins (or better) ... Tessa had three good paternal matches, one at each site.

23andme match

The surnames of many of the paternal matches looked New Mexican to me (endogamous!)

When I lived in Albuquerque, I learned a great deal about the early Spanish settlers of that area so I was happy to help Tessa find her unknown Dad

23andme match

The 23andme match was the grandchild of (Jose) Pasqual PADILLA sharing 5.1%  

or 368 cMs.


Based on his other matches and their ages, the 23andme match was confident that he was the half 1st cousin of the Padilla father we were looking for; that Tessa's grandad was a son of the 2nd wife of Pasqual Padilla,

thus a half first cousin once removed - Half1C1R  to Tessa

The Ancestry and MyHeritage matches shared common ancestors: surname MARTINEZ

23andme match

The Ancestry match - 287 cM - had a tree with just parents. Building that tree in our research tree we found common ancestors with the My Heritage match of 282 cM

Eugenio and Maria Martinez

but they were the great great grandparents of the Ancestry match. Jose Trinidad Martinez, the son of that couple who was the Ancestry match's grandad had several wives and many children - so perhaps another half 1st1R?

Obituaries are a great source for finding the names and parents of the living. This one for Trinidad Martinez from the Albuquerque Journal found the Martinez-Padilla pairing we were looking for

Next task was to see if we could find a daughter of (Jose) Trinidad Martinez married to a son of (Jose) Pasqual Padilla

So did Pasqual have a son named Luis?

23andme match

MyHeritage match

Ancestry match
9 Sons

Yes Pasqual's son Luis married Teresa Martinez! the daughter of (Jose) Trinidad Martinez

So which of those 9 sons was in California at the right time?

Only 2 of them 

Meanwhile Julie, a daughter of one of the possible half brothers, tested independantly at 23andme and shared 774cM (about 10%)

with Tessa

Now Tessa showed off her sleuthing skills, she called the librarian of the small town that most of these Padillas were from and got copies of their obituaries and lots of information. Neither possible father was still alive but she tracked down a son of each one of them and talked them into testing

So Julie is either a half niece or a 1C1R

image from Blaine Bettinger's chart 2017

Here are the tests results that came in

for her possible half  brothers at Ancestry

Tessa was welcomed into her father's family; here she is with her half brother and half niece

BioAncestry can often help greatly with unknown parentage. Adoptee Amelia was told that her mother was Italian and her father a Hungarian musician and that they died in a car crash

As you can see, one parent was actually Jewish and the other Italian.

It helped to go through her matches and star all the jewish side

Many automated tools can work with just the "favorites" aka starred

Amelia had a group of Jewish cousins who were all members of the Epstein family

The most likely father based on matches, age and place was J. Epstein but his son's test came in with only 384 cM so not possible

Plus Amelia's two best matches had no Epsteins in their trees although they were high shared matches with all the Epsteins

Thanks to Rocco Hindman of L.A., we found the answer: Bonnie's father must have a different father than the one of record. Amelia had matches to the line of the grandmother of Bonnie

The matches to the family of the wife of C. Epstein were distant and not convincing

Bonnie's paternal grandmother had only the one child 12 years after she married a Hungarian Jew! 


That son was a musician!


Our theory, which works with all the matches is that she used C. Epstein, unmarried at the time, to father her child


If that child is Amelia's father then Bonnie is her half niece


On Ancestry, although there were enough relatives on the Jewish side to find her late father, there are very few Italian matches. MyHeritage is often better for Europeans....

MyHeritage is currently the only company that lets you sort by bioancestry and/or location, but again, there were not very many closely related Italians

We are still working on finding Amelia's mother

We found a few candidates in the list of NYC births,

none have panned out yet

She has sent for her original birth certificate,

(these are now available from many states)

The DNA methodology does not work as well when very few people from the extended family have done testing

Rocco is building trees down from the Sicilian common ancestors shared with 4th cousins

There are many automated tools to help with the process of finding unknown parentage

My favorites are:

GWorks from

DNA2tree (iPad, iPhone,

and Android only)


and DNA2tree

There are also many techniques to help with the process of finding unknown parentage

My favorites are:

The Leeds Method 

Building the trees of your matches is always the most important technique

Copying family groups from Ancestry Trees to my research tree



In order to upload a GEDCOM to Ancestry you need to create one

Pedigree Thief can create an Ahnentafel list from a pedigree on some sites:

  • A pedigree view on
  • An ancestor list on


Then you can use my tool to turn an ahnentafel into a GEDCOM

Another technique is to copy over family groups from the trees of your matches into your research tree at Ancestry

Start by clicking a person to copy and going to their profile

On the Tools menu, top right,

click on Save to Tree

Click on Add a new person, once this person is added, click your browser's back button twice to go back to the oriiginal tree and add this person again with the whole family group

to bring up this box

Now click the checkbox next to each family member you want to copy over and then Save to your tree

Another approach when the person is already in your tree is to use the trees on the Hints page

I check the checkbox for the trees with the most sources that have him and his parents

Then Review selected tree hints gets us the page where we can copy over each family member

You can keep repeating that as you build the tree up, go to his father's page and click on Ancestry Family Trees under Sources

A box comes up, click the View individual member trees

If the tree you copied him from has his parents then just click his name to go to his profile in that tree and use the Tools then Save to Tree to copy him with his family group from that tree


Common Ancestors

GWorks from is my go to tool for building a database of the ancestors of your matches

These are the names of the original Spanish settlers of New Mexico

The numbers of trees each ancestor appears in scream out ENDOGAMY

Earlier, I glossed over how I had the surnames for Tessa's paternal match ancestors, in fact I used GWorks

Jane had a third cousin match at Ancestry with a good tree

Can  GWorks can identify which line from the second cousin match is the one they are related on?

Top ten ancestors in GWorks

Can you find any GWorks listed names in the far right of the pedigree?

The Pratt Cranford marriage has 8 children

Three of them have DNA tested descendants, check the abbreviated McGuire diagram for clues

3 children


Surname frequency from GWorks can help you decide which children's trees to build down in an unknown parentage case

So the next step was to look for the surname of Pratt B's wife and then for child D's spouse

Targeted Testing

Child D's spouse's surname is in the database many times, now to get a child of D, a possible parent to test

Clustering is a powerful way to group your related matches together in a visual diagram, this one is from DNAgedcom

Each box in this diagram represents a grandparent line, you can change the low and high cM numbers to cluster. This one used 60-300 to get the nice boxes

This cluster diagram is from GEDmatch

This is the AutoTree Analysis

The next item is a list of results in a table with icons indicating when something could be generated

Cluster 2 is my Munson grandad

lets look at the autokinship by clicking on that icon

which brings up a new html page

Since so many of my MUNSON cousins are tested ...  what would autokinship came up with for that cluster 2 green box?

Lauritz + Josephine Monsen





Pretty accurate. I have identified which child of my great great grandparents each match is descended from. Only the last one is not correct, he is actually descended from a sister of Josephine's


A closer look at my cousins with the one generational correction


Ancestry has disallowed GENETIC AFFAIRS tool to cluster your DNA matches there


but you can color code your matches into 24 groups plus star your "favorites" 

On an iPhone or iPad find the DNA2Tree app and download it

DNA2tree is only on iPhones, iPads, and Androids via a paid subscription but it is a real game changer for unknown parentage searches

I decided to try DNA2tree for an Australian unknown father case that had only 4th cousin matches to see what it could do

clicking on Load Some Matches gets these options

Favorites = starred

Next click on Find Common Ancestors

Here is a sample set of Common Ancestors 

Note the repeating usernames (privatized) 

See what happens when you Merge Common Ancestors

Now there are only three lines, with no duplication of user names

Details of the Bugden matches

Click on Graph to see an image

like this

for the

Bugden matches


It did not all fit on the screen !


Note that the build tree function does not work anymore


GGrand parents

Grand parents

Thomas BUGDEN in our research tree at  Ancestry with all his children added by me

At this point I recruited an Australian search angel to build the tree down, looking for a descendant who married a Chinese person

BUGDEN pedigree for father's mother, full story here: has this paid product- I have not tried the new Android version yet

Another important tool is the ability to check if your parents are related, if they are this can make it harder to figure out the pedigree triangulation


This is a free tool at which checks just your DNA test

What About Y- DNA Testing?

Y 37 STR marker results for an Ashkenzi Jewish man

If you are from a population group who only took surnames in the last 100-200 years, a Y test is unlikely to give you a surname

But if you have Anglo Saxon roots, one surname may stand out in your list

2. Are there any close matches (1st cousins or closer), figure it out from there

3. Are there several second cousins who are not matches for each other? Build their trees

4. If you have DNA2tree, use it to find common ancestors and build a research tree or two

 5. Still puzzled? Run GWorks on DNAgedcom   and add trees collected elsewhere

  6. Might a Y DNA test help?


1. Use the "Are your parents related" (AYPR) tool at GEDmatch on the adoptee

To learn more take a class at

Or join Cece Moore's FaceBook group for adoptees

Or read a crime mystery novel from Nathan Dylan Goodwin

all images either screenshots or used by permission, note that the relationship images are from Blaine Bettinger's chart 2017

All my presentation slides are online at