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.
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.
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.
And 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
Well I think my one world tree talk was a success, although the web site I used for my presentation – slides.com – went down or was just inaccessible via the internet in the presentation room here at Rootstech. Perhaps it was the Amazon s3 site where the images are stored that was the problem.
Fortunately I had downloaded a PDF version as a backup so I used that. Maybe next time I will try the google presentation software instead.
I think my main point, that the most compelling reason to add your research to a one world tree is to keep it from ending up in the landfill the way my cousin’s did, came across well. My girlfriend Rochelle, who I am staying with, was convinced to add her research to one and even got herself a familysearch id today.
I have uploaded the rough draft of what I expected to say, much more wordy than what I actually said, to my downloads page under presentations. The URL for the slides which go with those words is
The side by side comparisons of the three one world trees start on slide 11
The comparison chart is kept up-to-date in my one world tree blog post.
And I will be doing this talk again for the Computer Genealogy Society of San Diego on the third Saturday in May.
The genealogy cartoon strips done by Esto Frigus at geneapalooza always lighten my mood.
This week I am too busy polishing my talk for Rootstech (this coming Friday at 2:30, Ballroom C) to write any posts. So instead I offer some humor from Esto that is quite relevant to the fact that I am flying to Salt Lake City tomorrow for a genealogy conference!
cartoon used by permission of Esto Frigus
Next week is Rootstech 2015! I can’t wait. I had such a great time last year. I met many of my facebook friends, fellow genetic genealogists, and genealogy bloggers in person and got to enjoy their talks.
I am pleased that this year I will be giving a talk, about the advantages of contributing your research to a one world tree. I will also compare the features of the big three, FamilySearch, GENI, and WIKItree. A topic that I blogged about last year.
Rootstech has a cool app for your Ipad, Iphone or Android which will track your schedule, your friends, and more. You can get it from the app or play store, just search for Rootstech 2015.