Wednesday, October 29, 2014

DNA News: Episode 6 of "Finding Your Roots" & 7cM and 700 SNP Threshold


Episode 6 of "Finding Your Roots" was another interesting episode. The theme was enslaved ancestors.  A highlight of the episode was the slave receipt for one of Nas' ancestors. I've never seen one of those before. Valerie Jarrett turned out the be 49% European, which wasn't surprising. She was surprised that Native American ancestry showed up in her DNA ethnicity results. She came out to be 5 % Native American. Her slave owner ancestors were wealthy, willing and able to cultivate her ancestor's intellect and provide materially for him. One of her ancestors attended MIT. It was uncommon for the mulatto children of slave owners to be treated like their legitimate children. It was very nice to see how the former slave couples legalized their informal slave marriages after they were freed. This episode gave substance to people who were often just nameless property while enslaved.

Two whole people , so far, at AncestryDNA agreed to compare results with me at GEDmatch. These matches pointed, again,  to the problem of the too strict criteria for matches at Family Tree DNA. I had around half a dozen people to compare these matches with. When looking at the total cM's, even turning down the shared cM's to 1, some of these matches would not pass the strict matching requirements at Family Tree DNA, even though they do share DNA segments over 10 cMs and have a proven paper trail relationship to my family. The 14.1 cM segment illustrated here is an example. I found other good matches that don't add up to 20 total cM's either. I think the 7 cM and 700 SNP threshold at GEDmatch should be a model for the testing companies to follow. They can rank the matches according to their own system, but please give us all of our matches that fall in the 7 cM and 700 SNP range. Family Tree DNA is great for identifying parents and close cousins, but as a genealogist I'm interested in more distant relatives.

I watched this great video which featured a presenter from AncestryDNA. It's filled with interesting information about their DNA testing program. The number of kits being processed every month is staggering! They process 30,000 to 50,000 kits per month.

I'm not completely emotionally prepared for the coming changes to our match lists at Ancestry. When I saw the new DNA symbol on the Ancestry matches' pages I jumped. I wondered if that meant we would see the changes Ancestry has been promising sooner rather than later?  I'm hoping we don't see another Family Tree DNA scenario with limited matches. I'm hoping it's more like 23andMe, which has a reasonable threshold similar to GEDmatch.

I've been continuing to create chromosome charts with segments from our matches. I'm collecting Forgey surname related segments. I used a suggestion from Kitty's blog to name the segments after ancestral couples. Here are the people the Forgeys came from.

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