Saturday, November 4, 2017

Brickwalls DNA and Privacy

AncestryDNA Changes

Sorry to hear that AncestryDNA plans on making changes which could hamper our ability to workout how we are related to someone. A match can now choose not to show up in results, and testers will be given the option to keep shared matches private. This is a positive development for those testing for ethnicity results who don't want to hear from matches, not so positive for the rest of us..

23andMe has managed to preserve privacy while providing needed tools like the chromosome browser and shared matches.

It's sad Ancestry has chosen to focus on ethnicity results rather than helping us to resolve our brickwalls. They've chosen to focus on the least accurate portion of the DNA results. Not providing the ability to map segments means the power of this tool will never be fully realized for their customers.

The only thing the ethnicity results can tell you with any accuracy is whether you are European, African, Middle Eastern, Native American or Asian. It can only give you vague estimates about anything more specific which actually may turn out to be completely wrong.

Working on Brickwall using DNA

After writing last week's blog post I downloaded my DNA matches from Family Tree DNA into Genome Mate Pro. Someone asked me about the DNA segment chart I included in that blog post. I was thinking it's been a couple months since I updated that database, so I needed to do that. The Family Tree DNA database has grown so slowly that updating every few months has been enough.

After completing the update to Genome Mate Pro I noticed that the Campbell match I was referring to at AncestryDNA has now transferred to Family Tree DNA. Great for me! She has a very complete tree going back about 6 generations at Ancestry. She has no tree or surnames at FTDNA so when I've been searching by the surname Campbell her name didn't come up. She transferred her kit recently.

Why is this such good news? The only information those of us researching Sarah Campbell-Wray have is that she married Anderson Wray in 1833, in Jackson County, Indiana and died there in 1848. We have a list of her children. All but two died before the 1880 US Census, when they would have stated where they thought she was born. Polly Thurman Wray-Hall stated her mother was born in Tennessee, but my ancestor Elizabeth Wray-Forgey didn't know where she was born?

With so little information, and the fact matches would be 4th cousins to my mother, probably removed by one or two generations, the segment data is crucial to making connections with DNA. I need to have a segment map which is as complete as possible in order to eliminate the possibility that we are related on another line. I have to rely on segments to give me clues. With these clues I can do further research in the actual surviving records.

Let's examine the exact segments shared with this match. Both my mother and I share the same segments and same and number of cM's with this match.

Chromosome 5, 28.05 cM's , SNP's 6100

Chromosome 18, 5.69 cM's , SNP's 1700

Chromosome 18, 22.27 cM's , SNP's 2443

We share a total of 56.01 cM's according to Family Tree DNA on 3 chromosomes. According to AncestryDNA we share 43 cM's on 3 segments.

Comparing these segments to others in the same places on the chromosomes it's looking promising that these segments do indeed relate to Campbell. They don't match up with any known Roller matches. They don't match up with any other surname segments.

Doing further comparison with shared matches at Family Tree DNA more good news! Half a dozen shared matches also have the surname Campbell listed in the surnames. As I stated before Sarah Campbell was said to have been born in Tennessee. Several of those who have Campbell listed have Georgia/Alabama ancestors. We know that there was migration heavy migration from Tennessee farther south. I was blown away when I saw two of these matches had Campbell ancestors who were from Greene County, Tennessee, which matches the place of origin of our AncestryDNA match. There was some migration from Greene County, Tennessee to Lawrence and Jackson County, Indiana. My Browning family migrated to these counties from Greene County, Tennessee.

Greene County sounds like a promising place of birth for Sarah Campbell? I will comb those records for any connections.

What I'm getting out of the DNA testing is confirmation of already well documented lines. DNA is matching the paper trail meaning there were no unknown adoptions etc. When it comes to my brickwalls more work is required. All of my brickwalls are at or beyond the 4th generation. The chances of matching a 4th cousin and beyond is far less likely. You have a 90% chance of sharing DNA with a 3rd cousin, but that drops to 50% with a 4th cousin and only 10% with a 5th cousin. Building a segment map using 2nd and 3rd cousins is the most effective way to workout those more distant matches. These large segments are more likely to be IBD, giving a firm foundation for those smaller segments.

I'm going to focus on building my segment map in hopes of narrowing down who is related on my brickwall Campbell line.



Deborah said...

Well done! You've inspired me to do some segment mapping!

Annette said...

Thanks Deborah! Mapping is helpful.