Thursday, November 20, 2014

Hitting The Earth: AncestryDNA Reality Check

Reality struck me yesterday when I learned approximately how much DNA I share with some of my AncestryDNA matches

There were many thousands of weak matches. Most are gone. Some extremely low confidence matches remain and they are now called moderate? With the old version moderate actually meant your match was strong. These old moderate matches are now generally called good to high. The moderate designation is now given to those sharing 6 cM's or less??? My designation would be Extremely Low for the moderate matches. As Ancestry states you may not be related at all to these matches.

Looking at some of my starred matches I've discovered that most are in the Good category, sharing approximately 6-12 cMs. I've actually compared with one of these matches and we shared a 14.7 cM segment. Another one of these matches in the Good category shares an 8 cM segment according to FTDNA.

I've been wondering how strong my important Owens line match is. I asked this match to compare at GEDmatch. They haven't yet. Now I see we are a Good match so I'll keep pursuing this match (this is a distant 7th cousin so I'm satisfied with 6 -12 cMs). Others that have dropped down to moderate I'll check against my Mom's matches to see if they have a better confidence level a generation back.

Our Browning matches look very strong ( High and Extremely high) and should help to extend our tree further back. It would be great if we could compare in GEDmatch?

Really the best thing coming from the changes for me is seeing exactly how strong a match is. That's the meat and potatoes of  all this.

Now that I have a better idea of how many cM's we share I can decide where to focus my attention. When they give the cM approximations, however, they aren't clear about what the total represents? It seems to represent the largest segment or segments?

My conclusion is based on the fact that when you include smaller segments the totals are much higher. I know this from looking at the same matches at Family Tree DNA. I share 41 cM's with a cousin at FTDNA but the probable range at Ancestry is much lower around 12 cM's -20. So, at least, they aren't totaling in tiny segments.

Extremely High Confidence
According to AncestryDNA the extremely high matches are at nearly 100% confidence level that you share a common ancestor in the past 5 to 6 generations. I figure this is the best place to start trying to establish connections. Going back over these matches I'm still only able to confirm a link with 3 out of 8 extremely high matches. I can't establish matches for 5 of these for various reasons. Mainly because my matches don't have trees going back far enough.

I am seeing 2 Campbells in the extremely high group which is my brickwall line. I'll be working on trying to find a connection with this line. Both of these Campbell lines are from Tennessee.

I understand that the AncestryDNA system for determining matches is more complicated than comparing segment size. For my own piece of mind I like using triangulation because the phasing process is not fool proof. I feel sorry for people like some of those at today's live broadcast who are relying completely on Ancestry to name their ancestors for them without questioning the process at all. An AncestryDNA "scientist?" is writing a blog post to tell us why we don't need a chromosome browser. Can't wait to see what the BS arguments are against it.

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