A second opinion on your DNA test can help your genetic genealogy research in several ways. Your DNA Guide Diahan Southard proposes several scenarios that can help you look at your DNA test results in a new way. (Retesting may not even be necessary!)

Second Opinions on a DNA Test

“Get a second opinion.” That’s the advice we hear about our healthcare and the tactic my kids use when one parent says, “No.” But it should also be a strategy employed in our genetic genealogy pursuits.

Second opinions come in multiple varieties. You can move your DNA test results between companies. For example, while you can’t transfer into 23andMe or AncestryDNA, you can transfer your autosomal DNA results out of all companies and into Family Tree DNA, MyHeritage, and now Living DNA. (Click here for step-by-step instructions.) This transfer gives you a second opinion on your ethnicity results. We have talked about how those numbers can differ between companies and your “real” values may be somewhere in between.

However, you may also want to get a second opinion for your match page. Because of different analysis methods at the various testing companies, the same match might be reported to share a different amount of DNA. Those differences should be slight, and shouldn’t influence your relationship. Remember that the amount of DNA you share is measured in centimorgans (cMs), and generally speaking, the more cMs you share, the closer your relationship. (Click here to read more about centimorgans.)

That total amount of shared DNA can help us with another kind of second opinion. Because DNA inheritance is a random event, the amount of DNA two cousins receive from their shared 2X great grandparents can be very different. For example, according to data collected form the Shared cM Project (SCP) individuals who are documented third cousins vary widely in the amount of DNA they share. They may share as much as 253 cM but as little as 6 cM!

However, you then get a new match in Isaac, who is a known third cousin, also a descendant of Jacob and Jillian, and you are sharing 86 cM. You then ask Isaac to tell you how many cMs he is sharing with Allen and he reports a whopping 92 cM! If we find the average amount of shared cMs between you, your sister, and Isaac and Allen, we get 65 cMs, which is much closer to the 74 cMs we would expect if you were truly 3^rd cousins. In this case we could say that the genetics supports a connection between these individuals at Jacob and Jillian.

While you could still be 4^th cousins instead of 3^rd, having a second opinion in your sister, and then a third opinion in your known cousin can be very helpful in determining your actual relationship to Allen. Of course, the only way to know for sure if Mark is the child of Jacob and Jillian will be to find the genealogical paper trail. But in the meantime, you can continue to look for more descendants of this couple who have been DNA tested, and get a more complete picture of your genetic relationship.

Disclosure: This article contains affiliate links and Genealogy Gems will be compensated if you make a purchase after clicking on these links (at no additional cost to you). Thank you for supporting Genealogy Gems!