Tag Archive | family tree DNA

Ancestry Composition Comparisons: a Case Study

Discovering where your ancestors came from is one of the more popular reasons to do a DNA test but the current ancestry composition algorithms have a long way to go. Sometimes East Asian ancestry is actually American Indian and South Asian might be gypsy or Indian Indian. Scandinavian might be British or North German and British and Irish might be Scandinavian.

Most efforts to analyze the deeper roots of your ancestry are based on samples of modern populations who self report four grandparents of a single ethnicity plus some public databases and a few ancient samples. Since each company relies greatly on their own databases of tested people, it is not surprising to see differences in their predictions.

My brother's Ancestry as shown at DNA.land

My brother’s Ancestry as shown at DNA.land

Since my brother is tested at all three companies I thought I would post the images of what each company sees in his DNA as well show the new report from DNA.land and a few from GEDmatch (both using his uploaded Ancestry.com DNA data). We are confident of our recent ancestry: 50% Southern Norwegian, 25% Bavarian German and 25% Ashkenazi.

The new DNA.land report is shown above, Hmmm, only 16% Ashkenazi.

Continue reading

Using an ahnentafel and the DNArboretum tool

There is a new tool, a chrome add-on called DNArboretum, that will generate an ahnentafel ancestor list from a Family Tree DNA tree or from the old format 23andme tree (not myHeritage).

An ahnentafel is a very clever and condense way to show all your ancestors. When trying to match up with a DNA relative it is particularly useful since you can quickly scan their ahnentafel for places and names in common. Obviously it would be better to automate that comparison but with misspellings and Norwegian names that has not worked well for me. However it might work for you, so click here for my blog post about how to use automation to compare GEDcoms.

MyAhnentafel

This is part of my ahnentafel as generated by DNArboretum from my tree at Family Tree DNA when logged into another account there. I clicked on my great grandmother Maren Wold and it bolded all her ancestors and descendants. Note that my parents are missing because they are marked private.

Sue Griffith of Genealogy Junkie has blogged in detail about how to install and use this tool at
http://www.genealogyjunkie.net/blog/dnarboretum-a-great-free-google-chrome-extension-for-viewing-trees-on-23andme-old-style-trees-and-ftdna

Continue reading

Please upload your ancestry DNA data to a site with a chromosome browser

Today I sent the following email to a newly found DNA cousin match at ancestry whose great-grandmother lived right next door to my family in Kristiansand, Norway in the late 1800s. She moved to the U.S.A just a year after they did (1884 and 1885) and lived a block away from where my grandad eventually lived on Ovington Ave in Brooklyn, N.Y.

Monsen Home KristiansandDear cousin,

OK now I REALLY want to see where our DNA matches, because I have a large database (spreadsheets) of where my Dad, my brother and I match various known Norwegian relatives so it is likely that I can figure out from the matching DNA segment(s) where we are related and if it is really the 7th cousin match shown at Ancestry.com on the Eigeland line.

Pretty please either upload to GEDmatch or Family Tree DNA or both.

First you will need to get the raw data from Ancestry.com – here is how:

UPDATE 15-Aug-2018: Roberta Estes has published a step by step on how to do this: https://dna-explained.com/2018/08/15/ancestry-step-by-step-guide-how-to-upload-download-dna-files/ Continue reading

Touring the Family Tree DNA lab

Some people when visiting Houston might want to go see the butterflies or visit the art museum but not me. On my first day here my choice was to go over to Family Tree DNA and take a tour of their testing laboratory conducted by Bennett Greenspan himself. Sometimes there are benefits to being a well known blogger!

 The Tecan machine

Bennett points out the Tecan machine, which adds chemicals to extract the DNA

The lab is remarkable for its use of robotics. Bennett said something to us along the lines of “knowledge workers should be doing knowledge tasks and robots the repetitive tasks. Hard to compete with China any other way.” It was great to see all those automated pipettes. It would have been nice to have those in our science labs way back when.

All of us genealogists who are using DNA testing to solve family mysteries have Bennett Greenspan to thank for starting the personal genome testing revolution in 2000. All because he was a genealogist who wanted to know if he was related to some possible cousins in Argentina and could not find it with the paper trail. He also had time on his hands due to selling his photographic supplies business. Here is the story in an interview he did on youtube: https://www.youtube.com/watch?v=4bq092MQUGQ

Continue reading

Triangulation: Proving a Common Ancestor

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.
Continue reading