Archive | December 2017

DNA makes a Merry Christmas

Yesterday was a very very happy day. Thanks to DNA testing, an 82 year old man who thought he had no kids, now has two wonderful adult children plus grandchildren and great-grandchildren. Merry Christmas Billy (my pseudonym for him)! Here is the story.

An accomplished and successful Florida business woman, let’s call her Cheryl, discovered at her father’s funeral that he was not her biological dad. His relatives told her and were not particularly nice about it. Cheryl knew that her dad, let’s call him Larry, had married her mom when she was three months along, but Cheryl had not known that Larry had a paternity test done and knew that she was not his child. He loved her mom very much, so chose to love and cherish Cheryl as his daughter. They were always quite close.

Her mother was long gone and could not be asked. In disbelief, Cheryl took the Ancestry DNA test to confirm or deny this tale. She also got her half brother, her mother’s son from an earlier marriage, to test. That way she could separate out the matches on her mother’s side from those from her Dad’s line.

Her DNA results had no matches to anyone in Larry’s family, which disappointed her, even though it was not a surprise now. However she found what looked to be a half brother, let’s call him Joe, an adoptee born and raised in Australia. Her other paternal side matches, two second cousins, and several third cousins, all had roots in a small town along the Mississippi River. Surprisingly. the second cousins had no ancestors in common with any of the others. So Cheryl contacted me for help back in early October.

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GENESIS from GEDmatch: the new chip

Technology never stands still. The latest change affecting all of us who love using DNA for genealogy is a new chip from Illumina. The past six or so years of autosomal DNA testing have shown that the current chip is great for testers with European ancestry, but does not have enough SNP coverage to figure out the details of the ethnic make up for people from other parts of the world. Many more and different SNPs are tested in this new GSA chip.

All the 23andMe tests done since this past July use that chip, as does Living DNA (highly recommended if you have British ancestry since it does local regional breakdowns). I imagine eventually the others will follow along. The bad news is that there is not that much overlap between this chip and the previous ones, which affects cousin matching.

Debbie Kennet wrote a blog post describing the new chip at https://cruwys.blogspot.com/2017/08/23andme-launch-new-v5-chip-and-revise.html

Because the SNPs are so different the DNA results from these kits cannot be uploaded to GEDmatch, however our friends there have built another site to handle these new kits called GENESIS. They have come up with a whole new algorithm for relative matching that works with lower SNP counts.

At the recent i4GG.org conference (videos coming in February), I gave a presentation on what’s new at GEDmatch, the second part of it went into much detail about GENESIS, starting with this slide:
http://slides.com/kittycooper/gedmatch-10-13-23#/38

The functions available at GEDmatch are being gradually implemented at GENESIS. Most of the key ones are there now. Plus there is some new functionality. One major addition is the showing of the number of SNPs actually overlapping between kits. Very important to know since the overlaps can be as small as 108,000 SNPs or as large as 580.000.
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