Sunday, July 14, 2019

The Case of the Missing DNA

A recent inquiry from a DNA match sent me into the mysteries of AncestryDNA matching. I was appalled at what I learned.

In the field of data science, we use the term "single source of truth." You would expect that DNA matching would be consistent across all the different testing companies, so any and all of them would be a valid source of truth. Not so. If you skip the story, please take a moment to look below at the explanatory graphic.

It started with a routine email from a gentleman I'll call Lou. He found our match on Family Tree DNA and asked if it was possible we were related through a particular surname. He closed by telling me he was of African-American descent.

Knowing the challenges faced by African-Americans who are researching their roots, I gave the email far more attention than I would have if it had been from a Caucasian match.

Lou and I had no shared matches on FTDNA, so  I turned to Ancestry, where I have identified many cousins from that branch of my family. But there was a problem. Our match on Ancestry was only 8 cM (1 segment), where on FTDNA it was 27 cM (3 segments). How is that even possible?

Our FTDNA match includes a couple of short segments. Eliminating them leaves our FTDNA match at 19.9 cM (1 segment), still more than double what AncestryDNA showed. We exchanged some emails to discuss the source of the data.

  • Lou had uploaded his AncestryDNA results to FTDNA, MyHeritage and GedMatch. 
  • Lou had tested with 23AndMe and uploaded that result to GedMatch.
  • I had directly tested with FTDNA and MyHeritage, in addition to AncestryDNA. 
  • I had uploaded my AncestryDNA result to GedMatch. 

All match combinations except AncestryDNA are in the range 17.8-19.9 cM, with one segment in the same approximate range in chromosome 12. Of course we can't see what AncestryDNA is suggesting.

Choose Your Source of Truth

My brother's match to Lou is also in a similar range to these numbers. At Ancestry DNA, Lou's brothers and daughter have a stronger match to me than Lou does. However, none of them have uploaded to GedMatch, so we can't see the science behind the numbers. This particular chromosome range does appear to fall in or near an ISOGG-documented slight pile-up area.

So this leaves the possibility that AncestryDNA has chosen to ignore some of the match due to pile-up. Wouldn't it be nice to be told that?

Does Ancestry have a computational error on my match with Lou, since Lou's daughter matches me more strongly than Lou matches me? Or does she match me in an entirely different way via her mother's lines?

What is the best source of truth? If you are using only AncestryDNA for your DNA matching, you are not seeing the whole truth. GedMatch is free. FTDNA is inexpensive. MyHeritage has some great tools. You can choose your source of truth.

Friday, July 12, 2019


To live in hearts we leave behind is not to die.
-- Thomas Campbell

Thank you to those of you who shared ideas for actions I can take at the time of entering a death into my family tree. Today I'm sharing those ideas, as well as the ideas they inspired.

It's all about remembrance of the family member who has passed. Take a few minutes to think and remember. What would future generations like to know about this person? What do I feel about the loss of this person? What are the actions that are appropriate?

  • Write a paragraph or a list of attributes about the person. Fully identify the person, the date of the writing and the author. Place it in my files, not online.
  • If memories are painful, consider writing them and then destroying them, perhaps through fire.
  • If there is a possibility to speak at the funeral or memorial service, make notes about what I want to share. I've been unprepared to share at a couple of services -- I can do better.
  • Update FindAGrave and/or BillionGraves. Create the memorial page. If the page exists, leave a message or add a photo.
  • Find the online obituary and capture it for my files. Leave a condolence message.
  • Do I need to send a card? Craft it (or buy it) and send it.
  • Create a scrapbook page to memorialize the person.
  • Create a memory book or shadow box. Consider gifting it to the family.
I hope these ideas will be useful to you, as they have been to me.

In closing, here is some scrapbooking inspiration in the form of a double-page paper layout. I created this several years ago in memory of my feisty maternal grandmother who I miss every day.

Thursday, February 28, 2019

Needed: A Data Entry Ritual

Do you have a ritual that you use when you put sad entries into your family tree? I don't have one and I need one, so I hope you will share if you have a ritual

I'm talking about deaths entered in near real-time. You receive a phone call, a text, an email or a message or post on social media. Someone in your family -- in your tree -- has died. It's a sad moment when I put that death into my family tree database. I'm not able to be detached and working in a research mode at that point.

It feels like I need more ceremony. A brief prayer doesn't feel like enough. If I were a Catholic, I might turn to my rosary.

In the past few months I've added a spouse for a granddaughter and a new baby. Those are new chapters and they bring joy. No problem. Entering older deaths also doesn't bother me. I can be detached when newly identifying someone who died 5 years ago or 200 years ago.

In the past year I've had to enter death details not only for my father, but also for two other members of the Greatest Generation. One was my Mom's second cousin, who was a genealogy mentor. The other was a distant cousin on my Dad's side who was a WWII veteran.

I know there will be far more deaths than births throughout the remaining years of my life. How do I honor those deaths? Do you have ideas?