Using DNA To Identify Biological Relatives ...So How Does That Work Exactly?

This is the number one question we get asked after finding a person's birth family by way of genetic genealogy.

Nine times out of ten, the very next question I get asked once I've told a client that I found their birth family is, "...but like, how does that work?'

They tell me they get that DNA was used to solve their case and that they trust the science, but they are curious as to how I can be so sure of the results I've found. So here it is: a super crash course in how we do what we do!

#1: Identify DNA matches.

Because of my background working law enforcement cases—which are worked much more behind the scenes—I'm used to not contacting anyone directly during the course of my case research. In other words, I typically do not need to contact a client's DNA matches to figure out who they are. This acquired skill comes in serious handy: when it comes to the many different DNA testing company websites and their communication features, no two are alike.

The built-in messaging platforms vary widely from site to site, so just because you send an excited message to a promisingly strong DNA match, don't expect to get a response anytime soon...or even ever.

In other words, you can never count on any of your matches to be able to help you in your search. Sure, it's nice on the rare occasion that it happens. But without a doubt, the most important thing I do each and every day is figure out exactly who a client's DNA matches are and then exactly how each is related to the other—without having to speak to any of them directly.

Pro Tip: Remember that if you were adopted, it is possible that only your birth parents (and in some cases, specifically only your birth mother, herself) may know of your existence. So don't count on any of your DNA matches knowing you exist, too! That's what we're here for.

#2: Good old-fashioned genealogy.

Once I've identified the key DNA matches on a given case and determined who they are, the bulk of what I do next is traditional genealogical research. I build tree after tree after tree... Family trees for days! I'm looking for patterns and lineage overlaps and photographically memorizing hundreds of surnames. (Yes, really. It is such an enormous help.)

Thorough, sound genealogy research is not for the faint of heart. Finding, vetting, and verifying family information and historical records is as tedious a task there is. A good genealogist understands this process and has put in the work to hone these skills so that they can not only do their job, but also stand by their results 100%.

Pro Tip: Never blindly trust the family trees your DNA matches may have made publicly visible on their Ancestry or other DNA test profile. More often than not, they are rife with inaccuracies—something that is usually unbeknownst to the DNA matches the trees have been built by in the first place.

#3: DNA math.

The final step is crunching the numbers. Once I've done as much research as I possibly can using the data available to me, I carefully calculate where a client fits into their genetic genealogy puzzle.

The simplest way to put it is this: There are only so many ways two people can be related to each other based on the amount of DNA (cM) they share. My job is to put that puzzle together in a way that accurately reflects the mountain of research. Sometimes I have all the right pieces and the assembled puzzle points me toward just one crystal clear solution for a client's birth parent(s). Other times, I can only get as close as a handful of solid scientifically-proven options.

At the end of the day, the puzzle comes together to provide information and ultimately answers. We don't need any information on the people a client is seeking...just DNA test results. There really is no better tool we could use! Because as we all know: DNA does not lie.

Pro Tip: Ignore the "relationship estimates" for each of your DNA matches, as provided by the DNA testing company sites. They are unnecessarily confusing. So much so, we could write a whole separate blog post about it!


So there you have it. Genetic genealogy is both an art and a science. If you find yourself, year after year, wishing for answers we are here for you! Reach out here.

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