While DNA passes from parent to child, each child only gets half of each of their individual parent’s DNA. Consequently, as a lineage is worked back in time, there will be ancestors in your genealogical tree with whom you might not share any DNA. It doesn’t mean that the ancestor is not your ancestor. It simply means that their DNA did not makes it’s way all the way down to you. While DNA is microscopically small, there’s only so much your body needs.
Some suggest (for example, Blaine Bettinger in his The Family Tree Guide to DNA Testing and Genetic Genealogy) that once a lineage is traced back to the 4th great-grandparents that there are paper genealogy tree ancestors with whom you do not share DNA. That’s why you may share no DNA with another descendant of one of your 5th great-grandparents.
Of course there have to be ancestors in your tree with whom you do share DNA.
9 Responses
What about a male testing Y-DNA? Would it not follow the male line all the way back and beyond the 4th-great-grandfather?
Y Testing does follow the patrilineal line. But you’ve got to have a strict father-son line of descent and the number of generations back to the match can’t be determined as closely as it can with autosomal DNA testing.
An Aha! moment! Thank you, Michael. I am sure I’ve heard what you wrote in the various DNA classes I’ve taken. However, you always say it in a way that clicks in my brain.
I have a 5th Great Grandfather that was an adopted child born in 1852 in Wisconsin, would there be a chance of ever finding family through DNA testing?
Potentially. That is starting to get to that point where the amount of shared DNA between cousins that far back can cause them not not appear on your DNA matches. But you could share DNA, so the test could be worth it, but it will take some analysis given the distance. I’d also test as many descendants of that ancestor as possible.
Thank you for this. I have also read an article that suggests the further away from the Common Ancestor, the less likely distant cousins will match DNA. I’m so thankful for my paper trail. It was suggested in order to figure out which particular line for a surname in my lineage was mine, I should attempt triangulation. But, and here’s the kicker, you have to have three cousins (no less than one generation below you’re own) to match for this to pan out. So far, I can’t find more than one. On either line. Face/palm. The surname in question at this moment ends with my 5th great-grandfather, as I cannot find his parents and so far no record of just when or where he was born.
Suffer me to say, this Brick Wall is giving me a head ache.
Definitely explained this concept very well in a few words, Michael. I am keeping this one to share.
Thanks. Glad you found it helpful.
My 2 x great paternal grandfather is my brick wall. I can find no parents or siblings for him he died before 1850 census. No death records, cemetery records, no land records.only records I have are his marriage in 1834 in Kanawha Co, VA, 1840 census of Louisa Co, IA, and a couple Of IA State census in 1840’s. My gr grandfather had 4 siblings, 2 died in Civil War (1had a daughter) , another brother that I can’t account for after 1870 and 1 sister. I have been in contact with several of her descendants. Is there a way that dna can help me find my 3 x great grandparents that far back?