30 Questions that Cover the Basics of Genetic Genealogy


Basics of Genetic Genealogy - 30 Questions to Get you Started

DNA testing results from commercial genetic genealogy companies contain clues to help you climb your family tree. Yet, how do you get started, and what do you need to know to obtain the most value from your test results to research your family history?


A DNA test result is a record of relationships without names, dates, or places. Further, DNA doesn't lie, but it doesn't tell the whole truth.


Understanding these two principles will help you use your results to provide another piece of genealogical evidence to trace your heritage and lineage.


The following list of articles and video links will help you understand the Basics of Genetic Genealogy. If you're new to using DNA to research your family tree, be sure to click on each question to read a more detailed answer.


  1. What can genetic genealogy tests tell me? Before taking a home DNA test, watch this video to learn what it can answer and what it can't.

  2. How do I take a DNA test? The process of taking a home genetic test involves one of two types - a spit test or a swab test. Thankfully 23andMe, MyHeritage DNA, Ancestry DNA, Living DNA, and Family Tree DNA have easy-to-follow instructions to complete the process. However, be sure you don't eat anything 30 minutes before taking your test.

  3. Is it safe to test with a genetic genealogy company? While no known direct medical harm comes from taking a home DNA test through your spit or saliva, the security of your DNA results is never 100% safe. In fact, anything you put online (or that government and commercial organizations put online for you) is not 100% safe.

  4. Are commercial genetic genealogy tests just a scam? It depends on how you define a scam. If you mean taking your money and giving you nothing in return? No, genetic genealogy companies are not scams. However, if you mean, companies take your money and give you results that you don't understand. Then, that's what the genetic genealogy educators, like myself, are here for.

  5. Who should not take a DNA test? While individuals who wish to protect their genetic information privacy should not take a DNA test, there are other situations where taking a DNA test is not advised.

  6. What is Y-DNA? Can it help you find your ancestors? A y-DNA test examines the Y sex chromosome, which only males inherit. The test can provide direct paternal lines, but there are limitations, and it's not the first test I recommend you take.

  7. What is Mitochondrial DNA? Should you take the test? This test explores the genetic material in your cells' mitochondria, which mothers pass on to their children. It helps you follow your mother's, mother's, mother's line. However, this test is the last test I would recommend you take, and only if you have a specific question on this line that can't be answered using autosomal DNA.

  8. Which DNA test is better? When it comes to testing your autosomal, y-DNA, or Mitochondrial DNA. I personally recommend autosomal for every genetic genealogist and the other two only if you have specific questions along your paternal or maternal lines that can not be answered using autosomal DNA.

  9. Do I only need to take one DNA test? The answer depends on the question you're asking. If you only want to learn your ethnicity to give answers at a party, then one test will suffice. However, don't tattoo the results on your arm). If you have a different question, then more than one test can aid your research. The only question is which combination of tests should you take.

  10. Do more genetic test markers matter? In the words of Obi-Wan Kenobi, “from a certain point of view.” There are really two aspects to this question - Autosomal DNA SNP and Y-DNA STR. While more test markers don't increase your autosomal tests' accuracy, more is better in Y-DNA testing ONLY IF your matches also have taken a test with more markers. ↪️ Do you want to learn more about genetic genealogy? Receive the DNA video and blog newsletter that will give you a weekly dose of new things to learn and try.

  11. Which DNA test is best for finding close relatives? All autosomal tests from any genetic genealogy company can identify who your close relatives are if they have taken a DNA test at the same company you have tested with.

  12. Can a DNA test prove paternity? Legally, it can not because there is a breakdown in the chain of custody of your DNA. However, genetic genealogists can use the results as evidence to identify close relatives, such as biological parents.

  13. Are my DNA test results WRONG? Your DNA test results are accurate for your close relationships. If your test reveals the mother you thought was your mother is not your mother, the DNA test results are accurate. However, you will have false matches the smaller amount of DNA you share with another person.

  14. Can DNA testing determine race? The answer to this question depends on how you define race. The answer is mostly no, but potentially yes, depending upon the genetic genealogy testing company you chose and the reference population your DNA is compared to.

  15. Are your DNA ethnicity results accurate? Ethnicity results from the commercial genetic genealogy companies are the least valuable information from DNA tests, even though they are the most advertised.

  16. What are reference populations? Commercial DNA testing companies calculate your ethnicity percentages by comparing your DNA with reference populations that have lived in identified regions for multiple generations. How much DNA you share with these populations suggests what might be your ethnic makeup.

  17. What is genetic inheritance? Using Legos, let me show you how your DNA recombines to create the patterns that help you create your biological family tree.

  18. How does DNA pass on over four generations? Mathematically, you inherit a 50% reduction of DNA from preceding generations. Meaning you receive 50% of your father's DNA, 25% of your father's father's DNA, and 12.5% of your father's grandfather's DNA. In practice, shared DNA is not going to be the same for every relationship. The more distant the relationship is, the more variability might see in the amount of shared DNA.

  19. Can DNA reveal if your parents are related? Yes. Yes, it can.

  20. Do twins have the same DNA? The answer depends on the type of twin. Fraternal twins are biologically different, but identical twins are, for the most part, genetically the same. We tackle even more DNA questions in our book DNA Q&A: Real Questions from Real People and Genetic Genealogy. Pick up a copy from Amazon today.

  21. How much of your parents' DNA do you and your siblings have altogether? While mathematically, you and your siblings receive 50% of your parent's DNA, due to the recombination of genes, your and your siblings might not capture 100% of your parent's DNA.

  22. How do half-relationships appear in DNA results? While we can all understand half-siblings, half-relationships becomes confusing as we climb our family tree. Case in point, what is the relationship between half-siblings and their aunt's children? Believe it or not, their genetic relationship is biological cousins. This article and corresponding video explain more.

  23. How many cousins do you have? Some DNA test takers have thousands of DNA matches. Many of them are cousins that you will find a shared common ancestor with. However, not every DNA match is a genetic cousin.

  24. What is a 2nd to 4th cousin? Many DNA testing companies have a label that identifies extended family relationships as 2nd to 4th cousins. What this label means is more complicated than it appears at first glance. Watch the video to learn more.

  25. What does MRCA stand for? This acronym stands for Most Recent Common Ancestor.

  26. How do small family sizes impact your DNA matches? If you descend from multiple generations of families with 1-3 children, that will dramatically impact the number of DNA matches you have compared to other test takers. In my wife's experience, that impact has been a disappointment in the possibility of breaking through her brick wall family lines.

  27. Why am I only genetically related to 120 ancestors? Autosomal DNA test results can only help you trace back to your 5th great-grandparents unless you have a parent tested.

  28. Will DNA tests tell me if I'm related to someone famous? It depends on whether a living famous person makes their DNA test results available to the public and has built a family tree to compare yours with. For deceased famous persons, it depends on where they appear on your family tree.

  29. Why take a DNA test when you don't have family tree mysteries? For you, a DNA test provides validation for your paper trail genealogy research. It also provides anchor points for others seeking out their heritage.

  30. How to handle unexpected paternity issues in DNA testing? There is always the risk that taking a DNA test may alter your family tree. When you discover a relative isn't biologically related in the way you genealogically expected, you should proceed cautiously.


While the above list of questions and answers is not comprehensive, you should be ready to move on to learning about ancestry research tools and advanced techniques to process your DNA matches. You can learn more about genetic genealogy resources by watching the following playlists on YouTube.

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