Doctor and Geneticist Tim Janzen Shares His Insight on Genetic Genealogy and DNA Testing in Three-Part Series

Dr. Tim Janzen

The world of genetic genealogy and DNA testing extend much further than just forensics and proving paternity. Dr. Tim Janzen, respected medical doctor and geneticist, uses DNA testing as a complement to genealogical research. In an upcoming three-part series, Dr. Janzen will help us to understand and embrace the processes better.

Photo courtesy of Tim Janzen

Photo courtesy of Tim Janzen

Over the coming days, Record Click will be publishing a three-part series of extremely interesting and informative articles that will help you to understand better about genetic genealogy and DNA testing. Our expert contributing author is Dr. Tim Janzen, a medical doctor and geneticist who has had an interest in genealogical research for more than 35 years, especially in phasing and autosomal DNA analysis. Dr. Janzen supports the use of DNA analysis as a complement to traditional genealogical research. He currently serves as co-administrator of the Mennonite DNA project.

In addition to running a family practice at South Tabor Family Physicians in Portland, Oregon, Dr. Janzen is a consultant to the genetics company 23andMe as one of their Ancestry Ambassadors. He also serves on the ISOGG Y-DNA Haplogroup Tree Committee.

Dr. Janzen periodically gives presentations on genetic genealogy and also does private genetic genealogy consulting on a case-by-case basis. His other passions include wife Rachel Janzen and their four children.


  • I’ve seen you a bit on the internet so it looks like you’re a genetic genealogy expert. I’ve noticed that virtually every African American that does an admixture test (with the exception of the AncestryBYDNA test from the DNA Diagnostics Center which is not to be confused with the’s Ancestrydna) gets a very tiny Native American/Asian percentage,even if they may not actually have absolutely any single trace of Native American/Asian ancestry. Why are African Americans getting these percentages if they do not have any such ancestry? Why don’t the tests just say 0%? And if an African American really does have actual and detectable Native American ancestry,how would one be able to tell if it’s real when every African American gets a Native American percentage?

    • Dear Reggie Jacobs,
      It appears that the predictions of Native American DNA found in African Americans as reported by 23andMe’s Ancestry Composition feature, the various admixture tools at GEDmatch, and similar tools are actually valid. Much of the Native American DNA appears to be the result of intermarriage among Native Americans and African Americans in the southern part of the United States before the Civil War, probably prior to 1800 in many cases. Sometimes Native Americans were enslaved and then intermarried with slaves from Africa. Roberta Estes discussed this in a recent comment on her blog at Some of the Native American DNA may have been brought to the United States by slaves who were imported from the Caribbean region prior to the Civil War. I discussed this in some comments I posted on June 1, 2012 on my blog at 23andMe at I recently reviewed the Ancestry Composition percentages of 19 African Americans who are sharing genomes with me at 23andMe. On average, these people have approximately 1.6% Native American ancestry per Ancestry Composition. The percentages ranged between 0% and 8.6%. You may also find this thread at 23andMe of interest to you:

      Tim Janzen

  • Dr Janzen
    Are you going to be doing any dna classes, or do you do 1 on 1 teaching. If so, what is your fee?
    Thank you
    Shirley Hathaway
    Happy Valley, Oregon

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