The Elusive Nature of DNA

If you remember your high school biology (or college – no, not you bio majors), and I am definitely oversimplifying here, we get our chromosomes from our mothers and our fathers in a complex process that mixes the 23 pairs of chromosomes of each, but ultimately results in our own unique combination of 23 pairs derived from each parent with their hundreds of genes which also shuffle and recombine, but not necessarily in equal amounts from each parent. In other words, we may have some pairs with genes that come only from one parent or the other, while others may be a complete mix. Obviously, some are lost along the way, since rather than adding together the chromosomes and genes of each parent which would have given us 46 pairs of chromosomes, the process leaves us with just our own unique 23 pairs. This brings me to a recent experience with my matches on AncestryDNA.

I tested my daughter and my niece. I am in search of my paternal Williams’ ancestors. I reasoned that if my daughter and I share the match but not my niece it must be a maternal match. If all three of us match the person it must be paternal. Those matches that match only my daughter are her paternal matches and similarly with my niece, matches we don’t share are, in this case, her maternal matches. My daughter’s test came back first.

100_0894-2I assumed that the 9 hints I already had would be shared by her, resulting in ten shared hints for each of us. Not so. My daughter only had 9 hints including me. The tenth hint that I have is quite clear and well documented, but apparently, the shared chromosome(s) must be missing from my daughter’s genetic profile. That’s a shame because that tenth match and I have developed a very nice email relationship, something that my daughter would have missed.

Perhaps even more startling were the results regarding matches with two paternal cousins in the database already. In this case, I thought that all shared matches with these two matches would confirm relationships with my father’s maternal family, while those that matched only my daughter and me would be paternal Williams’ or our maternal matches.  Great in theory, but didn’t work out in practice.

Much to my surprise, the two individuals who were already my matches, from my father’s maternal family did not match my daughter, neither of them. That was a shock. The two individuals are father and daughter. Genealogically, the father is my second cousin and therefore, the daughter is my second cousin once removed. The father’s grandfather and my grandmother were brother and sister. Until recently, I had only focused on the fact that we were matches. I never noticed that Ancestry said we had a different relationship than any of us believed.

I knew several other members from a different bclark-randolph-1ranch of this family. I’m not clear whether my father knew any of the members of this branch of the family. His sister knew them all. In fact, because of her age, she knew all of our family members back to our shared great grandfather. I, on the other hand, did not know this branch of the family until recently.  So, since I knew my father’s sister, and she knew each of these individuals back to our shared great grandfather, and additionally, she told me personally and wrote down in detail our genealogy, which my research confirms, Ancestry’s conclusions are a bit puzzling.  The only answer I can come up with is that we only got those small portions of our shared DNA that would normally be consistent with more distant relationships. What’s the lesson here? We need to test multiple family members which Ancestry advocates, because we can easily miss family members because our shared chromosome pieces have somehow not been transmitted to one of us. This can lead to false conclusions and missed relationships from common ancestry.

There’s another reason as well. Most of us, if not all of us who test are interested in our ethnic background. We want to know where we come from. Our test results give us a breakdown of our ethnic backgrounds. However, just as with other chromosomes with their many genes, those from our ethnic background are shuffled and reassigned to each of us. Again, just as with other genetic markers, the mix from my ancestry can be different from another family member’s, even a sibling’s. Thus, especially with smaller percentages of ancestry, it can be that one sibling gets trace amounts of a particular ancestry while another sibling gets none, or conversely, larger amounts of the ancestry. Again, an example from my results and my daughter’s may help explain.

My ancestry is, according to Ancestry, a mix of European and African, my Native American did not show up (although it has on other testing sites, a discussion for another time).  My daughter’s father was a second generation descendant of immigrant Jews from Eastern European communities that were shuffled back and forth between Russia, Romania, Ukraine, and Poland.  Thus, all of her African ancestry can be traced to me. My results on Ancestry indicate that I have 2% ancestry from the Ivory Coast/Ghana region. However, my daughter’s results indicate she has 7% ancestry from Ivory Coast/Ghana. Again, noting our European results, I have 8% Scandinavian, but she has less than 1% Scandinavian. I have 44% from Great Britain, but nothing from Ireland, while she has only 14% from Great Britain and 5% from Ireland.

Again, what’s the lesson? We must make sure to test multiple family members to maximize the information we can glean about our ethnic ancestry mix. We can’t decide because one of our expected ethnic ancestries is absent from our report that we absolutely don’t have that ancestry. We need to test other family members, especially siblings, to find and compare differences that can help provide a greater knowledge of our background.

So, let’s keep looking for our ancestors using DNA!

About mlwilliams

I have Masters degrees in Sociology and Religious Education which provide the backdrop for my interest in family history and community social histories. I've researched and written extensively on my Lassiter family, including my books: Miles Lassiter (circa 1777-1850), an Early African American Quaker from Lassiter Mill, Randolph County, North Carolina: My Research Journey to Home, and From Hill Town to Strieby: Education and the American Missionary Association in the Uwharrie "Back Country" of Randolph County, North Carolina. I am a frequent lecturer for the Family History Centers in the Washington, DC area, a former editor of the Journal of the Afro-American Historical and Genealogical Society, and have my own private research company, Personal Prologue.
This entry was posted in Uncategorized and tagged , . Bookmark the permalink.