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March 17, 2013

Confessions of a DNA Junkie

Is there a DNA Anonymous meeting nearby?

Several weeks ago I ordered the Y-DNA test for my brother. About two seconds later, I ordered the mt-DNA test for myself. We are awaiting the results (one week down out of the 4-6 week waiting period. Not that I'm counting or anything. Heh.).

Genebase, the company doing the tests, says this about the difference between Y and mt DNA:

The Y-DNA carries information about an individual’s paternal ancestry. The following characteristics of Y-DNA make it suitable for paternal ancestry analysis:
  1. It is found only in males and is inherited strictly from father to son (the same way that the surname is passed down).
  2. It’s genetic code is very stable (low recombination rate).
  3. It contains STR markers which can be used to trace an individual’s recent ancestry.
  4. It contains SNP markers which can be used to trace an individual’s deep ancestry.
  5. The Y-Chromosome is passed down directly from a father to all of his sons and remains relatively unchanged throughout the generations. For example, a distant male forefather will pass his Y-Chromosome down to all of his sons. His sons will then pass the same Y-Chromosome down to all of their sons in the next generation and so on. Thus, all males who are connected to a common forefather will have the same Y-Chromosome. This manner of inheritance is identical to the manner in which the surname is passed down in most cultures (i.e. from father to son along the male lineage). As a result, the Y-Chromosome will allow two males with the same or similar last name to determine whether they belong to the same original family line.

Determining your Maternal Ancestry
Your set of mtDNA markers is unique to you and your maternal line and contains valuable information about your maternal ancestors.  mtDNA is passed down strictly from mother to child.  By testing your mtDNA, you will be tracing the ancestry of your direct maternal lineage (your mother's, mother's, mother's..... maternal lineage).  The results of your mtDNA test allows you to trace your maternal ancestry in several ways:
  1. Deep Ancestry Analysis (mtDNA Haplogroup): Your HVR1 and HVR2 results will allow you to predict which mtDNA Haplogroup you descended from. Haplogroups are ancient family groups and the study of Haplogroups pertain to "deep" ancestry.  Unlike tracing family lineages in traditional genealogy, deep ancestry is a look at our ancient ancestral roots from tens of thousands of generations ago and shows how all people living today are connected to an ancient ancestor who lived in Africa over 100,000 years ago. To date, over 28 major mtDNA Haplogroups have been identified, and a unique set of markers are associated with each mtDNA Haplogroup. By examining markers in the HVR1 and HVR2 regions of your mtDNA, you can predict the mtDNA Haplogroup you most likely belong to. However, the only way to confirm the prediction is through mtDNA Haplogroup Backbone SNP Testing or the Coding Region Full Sequencing test which focus on additional markers in the Coding Region of the mtDNA.
  2. DNA Archaeology:  DNA testing has been used to answer many anthropological mysteries, ranging from the identity of the remains of the Romanov family to identification of mummies. With your mtDNA markers, you can compare your own mtDNA to the findings in these fascinating studies and see how you may be linked to ancient families and figures.
  3. DNA Reunion: By testing your mtDNA, you will discover the unique set of ancestral markers that were passed down to you from your maternal ancestors along your direct maternal line. You can compare your mtDNA markers to others to determine whether there is a possible maternal link. Such comparisons are useful for confirming or refuting existing research using traditional genealogy.
  4. Indigenous DNA:  Compare your mtDNA markers with a large database of indigenous populations from around the the world to see which population most closely matches your mtDNA type. 

Is all this boring you? Sorry, it is fascinating to me. And my parents. I remember getting the the family crest (hanging in my house at this very moment) they ordered (my guess - National Geographic). That was back when you sent a check in the post. My dad spent hours looking at microfiche in a library in Georgia. Of course, my mother could recite her family's genealogy going way back. 

I would love to have my sister and brother take the DNA test (it's a combo of haplogroups), just to see how their genetic pie slices up. 

According to a very nice man at Ancestry, the "uncertain" (in my case, 2%)  markers are tied to regions rather than ethnicity. My siblings could possibly have zero uncertain markers or they could have more. He also said that children who look more like one parent over another most likely got a bigger part of that parent's DNA. Based on that, my brother and I have a bit more of our father's mix and my sister would have more of our mother's. 
Think of your parents' DNA as a pot of vegetable soup with two potatoes, two carrots. Each bowl of soup will have a different proportion of veggies, some more carrots, some more potatoes, even though it came from the same pot.

Counting myself, I know five people who've done the DNA testing. Three of those are from the South, and each of them have an "uncertain" component. Two of them are from California - no "uncertain". 

That strikes me as funny.

My cousin asked me if I was nervous about the results. Absolutely not; I think it's exciting. But then, I wanted to be an archaeologist. This is kind of like that - only with myself.