Those five little words can be the most helpful words a genetic genealogist can hear. In fact, you may need to hear them regularly in order to rein in your enthusiasm, which may make the very information you are trying to share sail right over the heads of the people you are trying to share it with. After you have had your results and been working with them for awhile, it is very easy to forget how overwhelming they were when first received. No matter how much you read and try to prepare in advance of your results arriving, the best part of being new to the hobby is that you are blissfully unaware of how much you still have to learn.
Recently, I shared images of FTDNA’s chromosome browser detailing the inheritance pattern of 4 generations of my paternal family and blithely titled it, “4 gens: we inherited totally different segments from my grandmother.”
Right on cue, my cousin and traditional genealogist Mary came along with the magic words, “Please explain, I don’t understand.” Mary and I share great grandparents (the Kerns) and have worked together on our family tree for years. She hasn’t yet tested her DNA, but has mentioned she might like to.
I tried to explain. “This is a visual representation of the chromosomes of 4 generations (my grandmother, dad, me, and my sons). My grandmother’s chromosomes are the base image (with the rounded tips). Since my dad inherited 50% of his dna from his mother, you see his line (the top bar) as solidly overlapping each of her chromosomes. When I am added to the graph (you see my bar overlapping my grandmother’s beneath my dad’s bar- that represents what my grandmother and I have in common), I inherit about 25 % of her chromosomes. When her great grandsons are added to the graph, they inherit about 12.5%, but a different 12.5%, which results from genetic recombination (and also the reason you need to test, ’cause you got some Kern great grandparents DNA that I didn’t!).”
I expanded, “On chromosomes 19-22, only my dad inherited anything from his mother. All of us inherited nearly the entirety of her chromosome 9. My dad and I both inherited the bulk of several of her chromosomes, yet my boys inherited a varying range. For instance, Gavan inherited almost all of chromosomes 13, 14 and 16 whereas Jeremy got nearly all of chromosomes 15 and 18. Luck of the draw. When you look at all 23 chromosomes, it works out to the typical 12.5% inheritance pattern between a great-grandparent and great-grandchildren.”
I heaved a sigh of relief and hoped it made sense. With her reply, Mary brought me back down to earth with a thump. “How would they know Kern blood if no Kern has done the testing? I guess that is what confuses me. If all are alive and test then sure it’s easy, but if I only test what could be found out? I would love to do it, but if I don’t get many results it’s a waste, don’t ya think? I guess I am having a hard time trying to understand how they could get that info.“
I had one of my many genetic genealogical Ah Ha! moments. There is a reason for the cliche that we need to learn to walk before we can run. I had forgotten how totally confusing the subject is at first. I tried to un-muddy the waters I had mucked up.
“You and I both inherited from the Kerns about the same 12.5% percentage but not necessarily the same pieces. Just like in the chart, we inherited from our great grandparents the way my kids have inherited from their great grandmother, but they didn’t inherit the same pieces from her. As far as testing, the reward would be that you and I would match on certain segments, and as our most recent common ancestors are the Kerns, we would know those segments are from them. If anyone else ALSO matches us on those segments, we can then investigate their tree and see how we connect. That gives us the possibility of learning about generations further back.”
Then came the eleven little words that made all the explaining worth it, “I get it now! I really do want to do this!”
We all have brick walls in our trees, and we all have family lines we would like to know more about. Once you start working with DNA matches, it becomes apparent success depends upon other family members testing to help sort out how you relate to your matches. My parents testing lets me divide the matches we have in common into maternal and paternal piles, my grandmothers divide the piles further, and cousins like Mary narrow matches in common to very specific lines and give a real shot at bashing down walls. Sometimes, “Please explain, I don’t understand,” are the most important words for your genealogy project.