Legacy Tree Logo
    • Dansk
      • Auto
      • English
      • Spanish
      • Portuguese, Brazil
      • Zweeds
      • Norwegian Bokmål
      • Russian

juni 4, 2019 by Candace - Legacy Tree Genealogists Genetic Researcher 54 Comments

Why Don’t I Share Any DNA with My Known Relative?

One of our genealogists shares her answer to the question, “Why don't I share any DNA with my known relative?” after her own surprising DNA results.

Recently, Carolyn Tolman, Project Manager at Legacy Tree Genealogists, and I discovered we are fourth cousins. Her great-great-grandmother Rosa Clark is the sister of my great-great-grandmother Sarah Annie Clark.

Carolyn and Candace, fourth cousins.

Not long after we made the discovery, we were sitting in a DNA chromosome mapping session together at Roots Tech. I leaned over to her and suggested we use our shared DNA to begin mapping our Clark DNA. We logged into our AncestryDNA accounts immediately but couldn’t find each other in our match lists! What if one of us had misattributed paternity? What if one of us is not biologically a Clark?!

Maybe we had just missed each other while quickly scanning our DNA match lists. Thousands of matches aren’t easy to skim through, especially while listening to a lecture. We moved to GEDmatch where we could quickly compare our kits in a one-to-one autosomal DNA comparison. (Autosomal DNA includes all your chromosomes except your sex, X and Y, chromosomes.) The results were definitive. We share no DNA—zero centimorgans.

why don't I share any DNA with my known relative

Why Don't I Share DNA With My Known Relative?

What do you do when you know you should be related to someone but you share no DNA? Is the analysis tool wrong? Do one of you have a big family secret waiting to be discovered? It’s not the tool, and regarding a big family secret—maybe yes, maybe no. It depends.

Because we get to analyze DNA results every day at Legacy Tree Genealogists, we knew that fourth cousins don’t always share DNA. According to a study cited by ISOGG, there is a 30 percent probability fourth cousins won’t share autosomal DNA.[1] There was no need to panic yet.

We decided to compare our DNA a generation closer. We compared her father to me—third cousins once removed—and still no shared DNA. I knew my aunt had tested and uploaded to GEDmatch so I located her kit number and we compared my aunt to her father. Almost 98 percent of third cousins share DNA. If they shared no DNA, then it would be time to consider the possibility of misattributed parentage on one of our lines. With relief, we discovered her father shares 28.7 cM of DNA with my aunt.

why don't I share any DNA with my known relative

The Role of Genetic Inheritance

why don't I share any dna with my known relativeYou might ask why I share no DNA with Carolyn’s father when my aunt does? My aunt’s DNA contained segments that either my mom did not inherit or that my mom did not pass on to me. This is why it is so important to test multiple relatives and examine each of their DNA match lists when solving a DNA mystery.

You might also notice that Carolyn’s dad and my aunt share a low amount of DNA for their proposed relationship. In fact, this amount of DNA has only an 8.87 percent probability for third cousins. Does this mean there is a different relationship, not third cousins on the Clark line, that is the real relationship? Is there STILL a big family secret? We scanned our match lists for a key match—a descendant of Annie and Rosa’s siblings—someone we would both match but is independent, not descending from either Annie or Rosa. Such a match could help in confirming that neither of us have a break in our biological line. Sure enough, we found a match descended from a brother of Sarah Annie and Rosa who was on both our match lists sharing a reasonable amount of DNA with both of us. We could search further finding additional matches who descend from other siblings.

Because of the document evidence showing our relationship and the DNA evidence between Carolyn’s father and my aunt, and our shared Clark matches, we can reasonable conclude there are no family secrets in our Clark line and we really are fourth cousins, by blood, even if we share no DNA.

If you’ve taken a DNA test and need help analyzing the results, or if you have a genealogy question you think DNA might be able to help answer, we would love to help! Contact us to discuss your questions and goals, and we’ll help you choose a project option and get started.

 

[1] ISOGG Wiki, “Cousin Statistics,” International Society of Genetic Genealogy, https://isogg.org/wiki/Cousin_statistics, accessed April 2019.

Filed Under: Adoption & Genetic Genealogy

Skriv et svar Annuller svar

Din e-mailadresse vil ikke blive publiceret. Krævede felter er markeret med *

  • Home
  • Careers
How to Hire a Professional Genealogist
Terms of Use Privacy Policy

© 2004 - 2025 Legacy Tree Genealogists. All rights reserved.

Cookie Consent

This site uses cookies to enhance your experience. Consent allows us to track browsing data. Opting out may affect functionality.

Functional Altid aktiv
Storage or access necessary for enabling the use of services requested by the user, or for the sole purpose of communication over an electronic network.
Preferences
Storage or access necessary for the legitimate purpose of storing preferences that are not requested by the user.
Statistics
Storage or access that is used exclusively for statistical purposes. The technical storage or access that is used exclusively for anonymous statistical purposes. Without a subpoena, voluntary compliance on the part of your Internet Service Provider, or additional records from a third party, information stored or retrieved for this purpose alone cannot usually be used to identify you.
Marketing
Storage or access required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes.
Vælg muligheder Administrér tjenester Administrer {vendor_count} leverandører Læs mere om disse formål
Preferences
{title} {title} {title}
Cookie Consent

This site uses cookies to enhance your experience. Consent allows us to track browsing data. Opting out may affect functionality.

Functional Altid aktiv
Storage or access necessary for enabling the use of services requested by the user, or for the sole purpose of communication over an electronic network.
Preferences
Storage or access necessary for the legitimate purpose of storing preferences that are not requested by the user.
Statistics
Storage or access that is used exclusively for statistical purposes. The technical storage or access that is used exclusively for anonymous statistical purposes. Without a subpoena, voluntary compliance on the part of your Internet Service Provider, or additional records from a third party, information stored or retrieved for this purpose alone cannot usually be used to identify you.
Marketing
Storage or access required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes.
Vælg muligheder Administrér tjenester Administrer {vendor_count} leverandører Læs mere om disse formål
Preferences
{title} {title} {title}