What’s the value of AncestryDNA for life story professionals?
Why is one sibling’s AncestryDNA results different from another’s? If we share the same parents and grandparents, how can our tests show something different? Is genetic genealogy incompatible with family heritage?
You share an average of 50% DNA with your sibling. But that’s just an average. Theoretically, you could share 100%—or 0%—of your DNA with a full sibling.
Genetics and family history don’t line up exactly.
In this episode, we discuss a simple overview of how genetics work, including:
- how DNA carries the genetic information
- how the DNA is packaged in chromosomes
- how we each have 23 pairs of chromosomes—22 pairs of autosomes and 1 set of sex chromosomes
How are these genetic “packages” passed down?
You don’t necessarily get 25% of the DNA from each of your grandparents because of the way the DNA is packaged. Some grandparents may be under- or overrepresented in your DNA pool. The deviation from the average gets greater and greater the farther back you go in your family tree.
The “packages” of DNA in a chromosome—e.g. all of the genes on Chromosome 1—don’t get mixed up. The set of genes are arranged on that chromosome, and it holds steady.
Interesting fact: By the time you get back to your great x5 grandparents, there are more grandparents than there are number of chromosomes.
Genetic genealogy makes some assumptions
For example: if you trace your family back to the Mayflower, that’s going back nearly 400 years, or 15+ generations. The probability of you having any of the DNA of an ancestor who came over is very low.
These relatives exist in your family tree, but probably not in your DNA.
Genetically, you’re not like a glass of water, infinitely divisible. Because your inheritance is packaged in these chromosomes.
In her Facebook group, Family History Writing and Photos, Lynn Cobine posted a message stating that the average British person’s DNA is 36% British. (One British member got results back from AncestryDNA saying she was 1% British!)
What does this mean. And how are the genetic tests conducted?
They don’t sequence your entire genome (yet).
Mike gets into the science of genetic sequencing, explaining concepts like the double-helix, SNPs, base pair rules, and how genetic data from different populations are considered representative of certain regions.
The upshot? The science is real.
However, we need to bear in mind that there are certain assumptions inherent in the scientific process.
A few things that genealogical genetics can show:
- They know the SNP markers for Neanderthals; there was interbreeding between Neanderthals and humans, and that can show up in your DNA.
- DNA genealogy also shows migration patterns in humans.
- Exchange of DNA can cross between members of pairs; it occurs during the formation of the sperm and egg. The chromosome as a completed self-contained package isn’t 100%; over time there’s a little bit of seepage between them.
- There are ancestors from which you will have inherited NO DNA.
In the end, we’re ALL related to each other because we’re part of the same species.
The nuclear genome isn’t the only genome in town.
Introducing the mitochondrial genome. Inside most cells are mitochondria, the powerhouses of the cell, where ATP is made. The mitochondria are derived from bacteria, which are in turn descendants of ancient bacteria. Our cells are fueled by these descendants, providing the energy they need to survive.
The human egg is a huge cell. A nucleus and a huge amount of cell surrounding it, with the mitochondria. The sperm basically injects its DNA. That fertilized egg divides and develops, and during that process of cell division, the mitochondria are dividing as well. We get ALL of the mitochondria genome from our mothers.
In essence, we can use the Y chromosome to trace in the male lineage back through a single line of descent, and the mitochondrial genome to trace back through the maternal line. It’s a great gift of nature to scientists.” —Mike Tones
Iceland, a case study
DNA analysis showed that the male Vikings who raided and settled Iceland didn’t take along their Viking women, but swung by Scotland and Ireland to capture new females. So the population of Iceland is descended from male Vikings and female Scottish and Irish women.
Want to know more about AncestryDNA and Viking migration patterns? Check out what Mike Mulligan has to say about it.
Family/cultural ancestry vs. genetic ancestry
At a DNA level, the story of our ancestry may be different from how we see it culturally. There may be times when those things are in conflict with each other; that’s when you have to hold two apparently contradictory things in your mind at one time.
There are isolated populations in the world, but at the end of the day, we’re all mutts who trace our roots back to Africa.
Genetic variation within a population is much greater than between populations.
The real value of AncestyDNA for life story professionals?
It may be what AncestryDNA itself touts on its website:
“You’ll also be connected to living relatives who share parts of your DNA. And since Ancestry has the unique ability to bring together DNA results with 100,000,000 family trees and billions of historical records, we can also help you fill in pieces of your family history.”
A huge database that will connect you to family you didn’t know you had? That may be just as exciting for life story writers and legacy professionals as it is for genealogists.
Greg Cronin wrote this after being surprised by the results of his AncestryDNA test. I read only a part of it on the podcast. Here it is in its entirety:
“For My Ancestors,
I write during a period of identity questioning. Today, my genetic analysis sprung some surprises on me – surprises are a normal part of life, but these surprises were about WHO I AM, and where I came from. Cronin and Winsky, Irish and Polish, has been the neat, tidy story that I have just recently begun to investigate. The Cronins, Mocks, James, and Guys branches have been studied thanks to the hard work of a cousin. Two of my great-great-great-great-great grandfathers are identified. These two men are of utmost significance to me, as are all of my ancestors: I would not exist, if not for them. My children, and generations to come, would not exist, if not for them. This is a simple biological fact that should be better appreciated. I share 0.8% of my unique (as opposed to the 99.9% of DNA that all humans share – we are all one big human family) DNA with them.
I have 62 other great-great-great-great-great grandfathers (and 64 corresponding grandmothers of the same generation – I love them all and wish I knew them) who have not been identified.
The fact that they have not been identified does not make them less important. Serendipity prepared me for my ancestory information. I was blessed to be invited to participate in sweat lodge the night before receiving my DNA results. [Sage advice from a guy with 0% American DNA: never decline an invitation to participate in a sweat lodge with a Native American.] I hope Danny doesn’t mind me repeating what he shared. He has an Irish father and a Chicana mother: he calls himself a Leprechano. That is funny as hell, even without his delivery, and set the atmosphere for the sweat. With his wit and wisdom, we were asked to love and pray for our future, present, and past family. Universally, we pray for our children, grandchildren, and future generations. Brilliantly, as I rarely contemplated, Danny told us that my ancestors prayed for me, just as I pray for my children and future generations.
Wow!!!!!, my ancestors, my (great)x grandparents prayed for me.
Assuming from probabilities, my Nigerian ancestor was likely kidnapped and brought to America on a slave ship. I am 3.3% Nigerian. Each of my 32 great-great-great grandparents contributed 3.125% of my DNA. I have been reading slave narratives for the past month, and feel quite sure that of all my ancestors, the one from Nigeria prayed hardest, deepest, and most often for his/her future generations, including me. I want to know this person. I want to visit Nigeria, as much as I do Ireland, Poland, England, and north Africa.
I am Irish, who colonized nobody. I am English, who colonized everybody they could. I am Polish. I am Jewish. I am northern African. I am Nigerian. I am human.”
Fellow life story professionals, what role do you see genealogical genetics playing in your work? Is this something your clients express an interest in? What kind of impact does it have on the stories of someone’s life?
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