Archive by Author | Kitty

Lets All Help Collect DNA Statistics

Mar9

The DNA relationship statistics listed at ISOGG are invaluable for figuring out how you are related to new DNA relatives. This diagram shown there is a big help too:

DNA relatedness cousin tree courtesy Dimario, Wikimedia Commons

DNA relatedness cousin tree courtesy Dimario, Wikimedia Commons

More statistics would be even better so I am delighted to make the following request.

Genetic genealogicist Blaine Bettinger has decided to collect cM numbers for known close relationships from all of us who have tested. Read about it on his blog and then contribute yours. He wants family statistics out to 3rd cousins.

Blaine explains how easy to provide those numbers if you are tested at Family Tree DNA, but 23andme includes the X in their totals which skews the results. Plus they include segments smaller than 7cM which is not what Blaine wants. So I decided to make a step-by-step how-to for 23andme statistics collection.

Better is if your 23andme or Ancestry.com tested family members are all uploaded to GEDmatch.com. Then you can easily get the statistics there. Just run the one-to-many with the normal default of 7cM for each family kit and look in the columns Total cM and largest cM under Autosomal.

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I will be interviewed on a Genealogy Radio Show

Mar2
Photo of Scott Fisher

Scott Fisher, photo used by permission

Scott Fisher of Extreme Genes, America’s Family History Radio Show, will be interviewing me about genetic genealogy this week for his Radio Show to be aired next monday. Not sure how soon it will appear in the Extreme Genes archives, presumably sometime after the broadcast. The show is carried by 27 stations so check yours.

There are lots of interesting podcasts in those archives! Wondering if any of you already knew about this show and are regular listeners.

I will post more information here when I have it.

Triangulation: Proving a Common Ancestor

Feb26

The same question seems to come up over and over again among those new to autosomal DNA testing. If I match A and B on the same segment why is that not enough to prove they match each other and we have a common ancestor?

The reason the ancestor is not proven is that you have two strands of DNA on each chromosome (remember there are 23 pairs of chromosomes) and the testing mechanism cannot differentiate between the two of them. So A could match the piece from your mother and B could match the piece from your father or one of them could even be a false match to a mix of alleles from both parents (see my post on IBC for more on that concept)

The way to prove the common ancestor is to see if A and B match each other in the same place that they match you. This is what we call triangulation.

Triangulation example

Kristine’s shared DNA with other Wold descendants, relationships are to her (to me in parenthesis)

About a year ago I blogged about how, after many years, a change in spelling on the paper trail had led fellow genealogist Dennis to think his wife Kristine was perhaps descended from my great-grandmother’s brother Carl. To prove this I suggested he test her autosomal DNA.
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Rootstech 2015: my Wrap up

Feb16

Rootstech was held in conjunction with the FGS conference and was bigger than ever. Something like 25,000 people. The Expo Hall was twice as large as last year and full of a wide variety of interesting genealogical products in addition to the big companies.

Rootstech Expo HallAnd there was the temptation of the Family History Library just a block away. Many like me came a day or two early in order to enjoy research time in the library. And yes I did a happy dance when I found my new 3rd cousin’s grandfather’s farm entry showing his mother was indeed the expected sister of my gg-grandfather.

Judy Russell did a really good blog post on all the DNA news at the conference. I am very excited that Family Search will be partnering with Family Tree DNA to link from the FS tree to DNA results from ftDNA. Initially this will only be for Y and mtDNA. Plus testers at Family Tree DNA will have an icon that will link to their tree at FamilySearch when there is one.

A few of the Rootstech talks are available as videos at this url: https://rootstech.org/video/4050134760001 – I particularly recommend geneablogger Thomas MacEntee‘s talk of about his genealogy tool box on that page.

Fellow San Diegan blogger Randy Seaver did a comprehensive listing of Rootstech blog posts Continue reading →