To go Deep, or Wide, or Not at All

 

Perhaps this is the genealogist's question: to go deep or wide when researching family lines. At the beginning, for many people, the idea of going deeply into the past seems a compelling goal. How far back can we go? What will we find in the stories of past generations?

The advent of genetic genealogy may have upended the draw of that proposition. After all, a sure-fire way to locate those umpteenth cousins in our tree is to build out the branches of our ancestors' collateral lines.

For the most part, that is where I've focused my time. After all, with upwards of twenty thousand DNA matches—if you count all the distant cousins in the mix—it takes a bushy tree indeed to find a place for each of those cousins. That is mostly the point of my biweekly count, incidentally: keeping track of the expanding family tree and my progress in filling in the blanks.

But when I get to a case like Elizabeth Plummer's—my mother-in-law's sixth great-grandmother—it hardly does me any good to add that ancestor's siblings into my in-laws' tree. Why? Because most DNA tests show matches that are capable of reaching back to the sixth cousin level. That means connecting descendants of fifth great-grandparents—if those cousins even share any genetic material in common at all.

Since it's my husband who stands in as test taker for my mother-in-law's genetic legacy, it would be a rare match indeed that would connect him to his seventh great-grandmother Elizabeth. And examining descendants of Elizabeth's siblings would mean tracing the lines of an eighth great grandparent.

That is the result of using the most widely available DNA test, the autosomal test. If, however, we had used either the Y-DNA test or the mitochondrial DNA test (mtDNA), our reach could be extended even farther. But those tests, in our case, would not apply. For one thing, Elizabeth Plummer lies on my mother-in-law's line of the family, so my husband's Y-DNA results would be of no help there. But for the mtDNA test, we could almost have qualified. The necessary matriline held steady for six generations—but then veered off to that woman's father's line, before returning to that ancestor's paternal grandmother, Elizabeth.

And so, we are left in the nether reaches of genetic genealogy. Choosing to trace the lines of Elizabeth Plummer's siblings would be an exercise chosen simply for the fun of it. With so many other fifth and sixth great-grandparents still a mystery to me, I'd take that as my cue to move on to other family history puzzles.