Create a DNA Testing Plan

Diahan Southard

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A good DNA testing plan can help you solve family history mysteries and discover more about your biological family tree. Planning ahead helps you maximize your chances of success, set realistic expectations and use your time and money wisely.

Create DNA Testing Plan Why Family History IO.pngMost people pursue DNA testing for family history for two main reasons: first, because they have a biological or family history mystery they are trying to solve; or second, just because it seems like a good idea (everyone else is doing it, right?).

Whatever your reason, but ESPECIALLY if you are trying to solve a mystery, you need a plan. Otherwise you might spend way too much money on the wrong test, and way too much time analyzing results before finally discovering that test can’t tell you what you hope to learn.

Before you read any further…if you are looking for your own birth parent(s) and/or siblings, go to our Finding Your Birth Parents resource page. Download our free guide to what DNA can tell you about your birth roots (without having to connect with birth relatives, if you’re not ready for that step yet).

Create a DNA testing plan

Learn what kinds of questions DNA testing can answer.

DNA testing limitations What DNA Cant Do Limits of DNA Testing for Family History DNA Testing Goals 11 (1).pngCreating a realistic DNA testing plan means first understanding what DNA can and can’t do, both alone and in combination with additional research. So first, read my article on the limits of DNA testing for family history. Go ahead. I’ll wait.

Did you read it? Good. Now you know that DNA alone will not serve up the name of your unknown person. But it can, in combination with some savvy analysis and genealogical research. DNA alone will not nail down your exact genealogical relationship to someone. But it does give you a range of possible relationships, which, again, you’ll use along with that savvy analysis and genealogical research.

The kinds of questions you can answer also depend on the type of DNA test you take. Autosomal DNA tests* (from AncestryDNA, 23andMe, MyHeritage, Family Tree DNA or Living DNA) can help you rebuild your family tree and identify mystery relatives from the present generation back to about your 3X great grandparents. Depending on your question, you might also use Y DNA testing to learn about your paternal-only biological line (just the fathers) or mtDNA for your maternal line (meaning, your mother’s female ancestors). You can purchase Y DNA tests and mtDNA tests from Family Tree DNA. A best DNA testing plan often involves combining multiple kinds of DNA tests.

Choose a specific DNA question.

Now that you have an idea of the kinds of questions DNA can help answer, it’s time for you to choose your own question. Your best DNA testing plan will be based around a specific question. Here are some examples of questions DNA can help tackle:

  • Did my granddad and his brother share the same biological father?
  • Who were the parents of my great-grandmother, Jane Lewis?
  • Am I related to the Petrosyan family that lived in [place] in the late 1800s?
  • From what part of Sweden was my family?
  • Did the children in the family belong biologically to the first wife/husband or second one?
  • Was the father named by my ancestor’s mother really her birth father?
  • Have I identified the correct person/couple as the ancestors?

Learn how DNA can help answer that question.

Every situation is a little different—we can’t possibly address them all here. But I do walk you through all kinds of DNA questions-and-answer-paths in Your DNA Guide—the Book. That’s the best way to start learning how to use DNA to answer your family history question. But I do want to show you an example, so you can see how this works.

Example: “Who were the parents of my great-grandmother, Jane Lewis?”

Let’s say Jane was your mom’s dad’s mom—meaning, she’s not on your direct maternal line. The test to start with, in this case, is the autosomal test, which sheds light on both sides of a person’s family tree for about five or six generations back.

Now let’s consider how far back she is in your genetic story. You only carry about 12% of Jane’s DNA (you have roughly 50% of your mom’s, 25% of your grandpa’s), and only about 6% of the DNA of the people you are trying to find (Jane’s parents). So if we want to know more about Jane and her parents using DNA, we need more DNA. Most helpful will be the DNA of your second cousins, people who descend from one of Jane’s other children (or the descendants of your grandfather’s siblings). By finding and testing a second cousin, not only are you able to capture more of Jane’s DNA, but you will able to isolate the DNA you received from Jane and her husband (we can’t separate the two at this point) from the DNA you received from your other seven great grandparent couples. Eventually, you’ll be looking for third cousins who might be related to Jane’s parents, or even 4th cousins who might be related to Jane’s grandparents.

DNA testing…just for the record

For those of you who are testing as part of an overall strategy to document the most complete family tree (and to join the genetic genealogy party!), your testing strategy should be to gather autosomal test results from second cousins from each of your known ancestral lines at the great grandparent level.

You should also consider finding a direct paternal line descendant of each of your four great grandfathers to take a YDNA test from in order to represent the surnames of each of those lines. The Y-DNA provides a record of these direct paternal lines can help you sort out how different lineages with the same, or similar surname are related, among other things. Consider mtDNA testing to better identify female ancestors.

Keep recruiting your relatives to be tested. Keep building your family tree through genealogical research. The more you know, the more you learn! Gradually you’ll chip away at those genetic genealogy mysteries. If you don’t have a specific question on your mind yet, you’ll probably eventually come across one, and you’ll be better prepared to address it.

Want help creating your DNA testing plan?

I know there’s a lot to take in when creating your DNA testing plan. That’s why I’ve put together my free downloadable guide, “4 Next Steps for Your DNA.” WIth it, you can learn how to start sorting out your DNA matches and how to narrow down your relationship to those mystery matches that have been stumping you. Check it out today!

Get Free Download: 4 Next Steps for Your DNA

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<a href="" target="_self">Diahan Southard</a>

Diahan Southard

As founder and CEO of Your DNA Guide, Diahan Southard has been teaching people how to find family history answers in their DNA for several years, and she's been in the genetic genealogy field since its infancy. Diahan teaches internationally, writes for popular magazines, consults with leading testing companies, is author of Your DNA Guide–The Book, and producer of Your DNA Guide–the Academy, an online learning experience.


  1. Will

    Is there any test which will resolve if two female relatives are half sisters or aunt and niece?
    RGDS Will.

    • Diahan Southard

      Hi Will. I will email you.

  2. Mary Runde

    I am hoping I can identify connections to my 2xGGrandmother, Catherine McCarthy. Catherine was born about 1826 in Canada of Irish parents and she is a brick wall. Excited to see what I can find

    • Diahan Southard

      That sounds like a great research goal, and one that DNA can definitely help you with! Keep us posted on how it goes!

  3. Jo-Anne Gannon

    Hi Diahan. I am signed up for your study group on the 12th of April, and have Completed Steps 1 and 2 of your 4 next steps…Because of the distance between us in age, I find that my 2nd cousin’s granddaughter will be the one I need to connect to. I have located her (on facebook) and on….so have reached out! Hopefully I will be able to be in touch and request that she be tested?? So I am looking for our shared mrca who is MY great grandparents, and her 2x great. Will this work the same way?

    • Diahan Southard

      Your second cousin’s granddaughter would be your second cousin twice removed (2C2R). The common ancestors are your great grandparents and her three times great grandparents.

      Please double check the family tree and relationships before you have her tested. Is it possible to find a relative closer to your generation/age, maybe an older descendant from a different child of your great grandparents? There is a possibility you will not share any DNA with a second cousin twice removed!

      You might find value in a mentoring session to give you some feedback and ideas on targeted testing for your specific situation.

      See you in the study group!

  4. Roberta F Woods

    I have figured out everyone on my maternal DNA down to 77 cMs, but there are three individuals that are related to one another and I cannot find a common ancestor. The three share 171, 155, and 154 cMs with me. Only one has a partial tree. One doesn’t know who his father is and the other one refuses to communicate with me.

    What can I do now?

  5. Julianne Idleman

    There’s a typo on this page in this sentence, “You should also consider finding a direct paternal line descendant of each of your four great grandfathers to take a YDNA test ****from to **** represent the surnames of each of those lines.”


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