Part 497 - Smith Robertson Genealogy - I Am What?

24 April 2011

Evening,

Following up to my Posting, Part 496, I was/am somewhat confused by the differences on the results of my genealogy Autosomal DNA test results.

Recapping quickly – Ancestry By DNA, in 2005, returned the results that my genetic makeup should be 93% - European and 7% - Native or Indigenous American. Family Tree DNA’s results, in 2011, suggest that my genetic makeup is 95.9% - Western European and 4.1% - African. And my first gut reaction, “What the hell happened?”

Back up a minute, I am an English Teacher, a Treasury Manager, and a Diplomat-of-sorts, by trade, (now retired), and education. But I think logically… I think. How can my “supposed” scientific and gene-technological numbers be different? How did I, within six years, change my ethnic background and makeup? Something didn’t make sense to me.

I then decided to see a quick question to some of my respected mentors. My question was “Do you know of a specific reason why there is a difference between the Family Tree DNA and the Ancestry By DNA results?

Here are their answers -

From Megan Smolenyak Smolenyak –
The Ancestry By DNA “were the best available at the time, but the new ones would be more reliable. The differences have to do with different approaches being used to do the analysis.”

From Drew Smith –
“Different companies use different methods to test the autosomal DNA. They may look at different parts of the DNA. And ethnicity is identified by saying which ethnic groups are ‘most’ likely to have particular values at particular points in the DNA. In other words, you could test a particular point in the DNA, and say ‘the value you get is most commonly found among African populations’ (which is not the same as saying that it’s never found in European populations.)”

From Katherine Borges –
“One big reason that the results differ is because the two companies are using different databases and data sets to compare your results to. Even if you purchased your Ancestry by DNA test back when Family Tree DNA (FTDNA) was a reseller of the test, your results were still only compared to DNA Print’s database which does not have proprietary access to.”

And with those responses, and further reading in mind, I created the above inserted chart. I am an extremely visual person, albeit logical and I needed a “picture” to help me to understand. This basic Chart represents, in my mind, the different vantage points and testing factors of the two firms; Ancestry by DNA and Family Tree DNA. I have included, in green, a label representing 23andMe; I am waiting for their testing results.

This conversation will continue. Stay-tuned for more… as I pound my thick skull trying to make heads, (no pun intended), or tails of all the information.

Enjoy,

Jim

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