Finding Your Biological Roots Stories from a genealogy detective:
uncovering family secrets, reclaiming the truth and uniting families

Wednesday, March 31, 2021

Gina's Journey - Part 5: Using Triangulation

DNA Triangulation
Let’s backup a bit here and explain the process of Triangulation. The short explanation for triangulation is comparing the results of three DNA matches who are not closely related to find a shared segment on the same chromosome with the length of 7 centimorgans or greater. A length of less than 7 cMs might be a false match and therefore should be discounted.

An overlapping match on the same segment with greater than 7 centimorgans indicates all three DNA cousins share a common ancestor. The best way to view this three-way comparison is by using a chromosome browser (available through 23andMe, MyHeritage and GEDmatch). If the matches you are using for triangulation as well as your own results have attached, well-researched family trees, you can compare the three trees and hopefully find the most recent common ancestor (MRCA) shared between the three DNA cousins.

If you are utilizing the tools at DNA Painter for analysis, “paint” this specific chromosome segment onto your DNA map and assign it to the MRCA shared by you and your two matches.

Let’s simplify this in terms relating to Gina – by finding a shared, overlapping piece of DNA between myself, Gina and another cousin, I had found an ancestor who could be Gina’s birth father’s 2nd great-grandmother! This was still a wide span of four generations, but I was inching closer!

Glancing once again at my chromosome browser displaying shared centimorgans for two DNA cousins in a colorful spread of purple and orange bars, it was apparent I had more in common with both Gina and Debra than just that one great-grandparent! But our section of shared cMs on chromosome 20, although small, was confirmation that I was on the right track!


DNA Triangulation



Wednesday, March 24, 2021

Gina's Journey - Part 4: A Clue in the Chromosome Browser Comparison

DNA double helix
It was all too apparent, Gina and I had numerous crossovers between our ancestral lines and they all originated in the same endogamous community. There was one other tool at 23andMe that might offer an answer – the chromosome browser.

I navigated to “Advanced DNA Comparison” found under “Family and Friends” in the main menu and plugged in Gina’s name and the match that shared the same surname of our possible third great-grandmother, then clicked “Compare”.

If all three matches were descendants of the same ancestor, at least one segment of overlapping DNA should show up in the chromosome browser. At the top of the page it stated I shared 82 cMs with Gina and a bit more with our other cousin match at 104 cMs. Let’s call this cousin Debra. The results were neatly illustrated with bars for each of our twenty-two chromosomes plus X, being the 23rd chromosome. Gina’s shared DNA with me was color-coded in purple and Debra’s in orange. I shared DNA on five segments with Gina and on seven segments with Debra. But the three of us shared just 13.45 cMs together - all on one segment.

I had hoped for a bit more DNA shared between the three of us, but this amount did fall within the range of 4th, 5th or 6th cousins, and of course there were many in-between variations such as 5th cousin, once removed and so on (see DNA Painter – SharedcM Project for a full range of relationships based on shared cMs). This was an exciting discovery and a good triangulation match, pointing to a specific family line I had already documented in my genealogy research. Without directly accessing Gina’s DNA results or sorting through her matches, I had found a major clue to her paternal line using triangulation.


DNA double helix



Friday, March 12, 2021

Gina's Journey - Part 3: A Genetic Clue at 23andMe

Genealogy Research
When presented with an NPE mystery, especially one tied to my personal DNA, it tends to gnaw at my brain! My internal Sherlock Holms kicks in and I just can’t let it go. As Gina was an adoptee, I surmised she had probably tested with several DNA companies in order to cast a wide search net. Maybe I could track her down in another data base and gather more genetic info about our cousin match.

A day after our last message exchange, I logged into 23andMe and scanned down the list of DNA matches. My hunch was correct – Gina’s name was half way down the first page. According to 23andMe we shared 1.09% of our DNA – probably in the range of third or fourth cousins.  I clicked on Gina’s profile and scrolled down the page to view our comparison. I then clicked “Find Relatives in Common”.

Immediately I recognized a surname in our list of shared matches, that of a third great-grandmother through my paternal grandmother’s ancestry. Aha! That is exactly the direction I had guessed when viewing Gina’s shared matches on AncestryDNA. There was a good possibility that Gina and I shared at least one ancestor from this particular surname lineage. If the match was accurate and we shared a third great-grandmother, our relationship would be 4th cousins. Although it was a fairly distant match, I could build a tree forward from the 3rd great-grandmother and see if it led to a potential candidate as birth father.

To be honest, I wasn’t relishing the task as it would mean compiling a family tree containing five generations and many possible males who could be Gina’s father. Although this was an option, I decided to wait for Gina’s response before tackling a major tree reconstruction. If I could study her DNA results in more detail, I was sure I could narrow the search to the past three generations of her paternal ancestry.

As I studied my 23andMe shared cousin matches with Gina, it became murky with endogamous surnames! Not only did we share a great-grandparent related to one of my paternal grandmother’s line, we shared surnames related to all four of my 2nd great-grandparents through the same grandmother! Yikes! And our DNA waters became even muddier as I spotted at least three other cousins who I knew were related to my paternal grandfather’s ancestry! Oh for goodness sake, endogamy was once again to blame for a genealogy mess.

Genealogy Research



Tuesday, March 9, 2021

Gina's Journey - Part 2: In Search of Paternal Lineage

Old photo
I felt Gina was heading in the wrong direction and falling down a DNA rabbit hole. Maybe I could find her correct ancestral path. Since I did not have access to Gina’s AncestryDNA results and could only examine our shared matches for information, I had only one option: to explain the information I was able to derive from our limited comparison, and then ask for access to her results. I explained that by granting access, it would allow a thorough DNA investigation with the possibility of locating her paternal birth family.

Gina responded by sharing part of her story with me. She was in her late 70’s and had always known her adoption status. Since Gina’s maternal tree was attached to her AncestryDNA results, she obviously had found half of her NPE mystery by identifying her birth mother (now deceased) and several surnames connected to that lineage. Having been born and adopted in Illinois, and knowing her birth mother was a native of Illinois, Gina assumed her birth father must also be from the same state. OK – this information was something to go on, but I really needed to examine her DNA results for close matches as well as to sort her paternal and maternal cousins.

I wrote back with a brief history of my paternal family, although I could only offer a general idea of which great-grandparent line we had in common. And since it appeared both of us were from the same endogamous community, there was a high probability we shared more than one ancestral line. I gave Gina my personal email and offered to be a search angel for her, but I could only proceed if allowed access to her DNA results. I also encouraged her to share more of her story so I could understand just how much genealogical research had already been completed.

I patiently waited for a response – a response that took months in coming!

In search of her paternal lineage



Friday, March 5, 2021

Gina's Journey - Part 1: Adoptee Matches Deceased Relative

Ancestry DNA results
As with a number of adoptees who have contacted me during the past four years, Gina (not her real name) connected through AncestryDNA. She had a close cousin match with another kit that I manage for a relative who is deceased. Her first message to me was a standard inquiry, void of any personal information or reason for reaching out to a particular DNA match. I suspected she was sending the message out to all of her close matches with the hope that someone would return an answer. But as she was attempting to inadvertently contact a deceased relative and I was the administrator for this person’s DNA, I was apprehensive about sharing information and my private family tree with an unknown DNA match.

Before I responded to Gina’s message, I quickly did a scan of my own DNA results. Yes, she was there, but as a distant cousin relationship to me, sharing a much smaller quantity of centimorgans than with our deceased cousin. Applying Ancestry’s shared cousins filter, I immediately recognized Gina was related through my paternal (and endogamous) family line because all of our shared matches were color coded blue representing my father’s DNA lineage. Examining the long list of shared cousins, many of whom I recognized, it wasn’t hard to pinpoint our common ancestral line. But I didn’t have enough detailed DNA information to zero-in on our closest common ancestor.

My response to Gina was this: “I’m sorry, but I don’t know who you are or what you are looking for. I only share my private tree with cousins or people I am familiar with, and those who tell me the ancestors they are searching for.”

Although this was somewhat of a brusque reply, it did the trick! Gina answered back, telling me she was adopted and looking for her birth father’s identity. She had a list of suspected surnames possibly related to her paternal line and she believed they were all from Illinois. Well this was a surprise as none of the surnames she mentioned were on my tree, with the exception of one – and that was on my maternal side. From our shared cousin matches, I was certain our common ancestor would be found in my paternal family. This ruled out the one recognizable surname in her list which belonged to one of my maternal 2nd great-grandmothers.

 And there was another problem – all of my family, both maternal and paternal originated in Pennsylvania. Although there was a distant branch of my paternal tree in Illinois, Gina did not share any of these Illinois cousins with me or our deceased cousin. I was baffled!


Ancestry DNA results