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10 things to be aware of before you DNA test

Thinking about getting a DNA test? This list will help you be aware of what you should know before you get your DNA test.


1 – Know your end goal

Why do you want to DNA test? Is there a specific issue in your tree you are hoping to uncover the answer to? Perhaps you have been seduced by adverts to find your ethnicity. Maybe you are only interested in health history. Maybe you want to know the deep ancestry of your paternal or maternal line.

Knowing the answer to this question will help you decide which DNA test you should take, and you can find my specific recommendations in tip 5.


2 – Be prepared for the unexpected

This is the single biggest thing that I wish testing companies would make clearer.

It’s all fun and games finding out your ethnicity, but there are some truly heartbreaking stories out there. They aren’t even rare. Finding out that your father isn’t your father, surprise, you have several half-siblings!

Those trying to find birth family need to be prepared for rejection or perhaps finding out that your birth mother died just two months prior to you tracing her. Or maybe there is just a backstory that you would rather not be connected to; rape, incest, or perhaps finding out you are descended from a serious criminal. Rarely (thankfully), there are switched at birth scenarios.

Sure, there are fantastic stories of birth family welcoming new found children/siblings with open arms, but you do need to be prepared for a different outcome. Naturally, everyone hopes for a fantastic outcome, but it’s a real possibility that the opposite will be true. I strongly advocate counselling; regardless of whether you have reason to believe what you find out may be emotionally difficult, or if you test and results are not what you expected. Make sure ahead of time that you know how to access counselling should you need it.

3 – Be prepared for no answers at all

Some people will get their DNA results and be extremely disappointed when it turns out that no close relatives have tested.

This could be because they descend from a particular area where DNA testing is either non-existent, or very much in its infancy. Even where DNA testing is more common, this is still a relatively new science, where a minority of the population has tested, and it may take years to find any clues at all.

Or you might descend from a community that is unlikely to DNA test. For example, close-knit communities with a strong oral history tradition, who know whose family is whose, and who someone descends from are unlikely to DNA test because they don’t see the point. For an adoptee descended from such a community, that can be extremely frustrating.

4 – Privacy and Informed Consent

This is a big one, particularly if you are asking others to test on your behalf. You may feel that you are prepared to go ahead no matter what, because you want answers. This is how I felt when I first tested. Whichever test company you use, make sure you are comfortable with their privacy policy and what they will do with your results. Think carefully before you upload any raw data to projects such as Gedmatch; since this can be accessed by anyone and used for pretty much any purpose including criminal investigations, as recent press stories have highlighted. This usage will only increase as time goes on. Maybe you think ‘well I’ve never done anything, why should I be worried’, but how would you feel if it turns out that you are closely related to say the Golden State killer or the NorCal rapist? A small likelihood to be sure, but it’s important to be aware of.

Make sure, if you are asking relatives or potential relatives to test on your behalf that they understand what can be done with their DNA, and what might be uncovered. I’ve heard of a situation where a mother didn’t understand that her sample would show she had had another child. Another situation with a similar circumstance where a mother forced to give up her baby had literally blocked out that she had ever been pregnant, let alone gave up a child for adoption, due to terrible treatment in a mother and baby institution in the 1950s. As you can imagine, this caused severe mental trauma for both mother and the adoptee. More amusingly, I recently saw an episode of Forensic Files where the culprit didn’t understand what DNA was and readily volunteered to give a sample in a town-wide request because he didn’t understand that it would prove he was the culprit!

5 – Who should you DNA test with?

Knowing why you want to DNA test can help you decide which company to test with, and what kind of test you want to take.


I’m interested in deep ancestry

If you’re only interested in deep ancestry, you’ll likely want (or want a biological male relative to take, if you’re female) to take a Y-DNA test, which will take you to the deep ancestry of your paternal line only (father’s, father’s, father’s, father’s x a lot father), or a Mitochondrial DNA (aka mtDNA) test (either sex) which will do the same for your mother’s line. This narrows down your testing company choices to either 23andMe or FamilyTreeDNA. Personally I would choose FamilyTreeDNA for the simple reason that more extensive testing (at a price) is available from FamilyTreeDNA so it keeps your options open should you want to delve even deeper. For example, for those interested in the paternal line, taking a Y-DNA test (I’d suggest the Y37 or Y67) enables you to later purchase what FamilyTreeDNA calls the ‘Big Y‘. This enables you to get your haplogroup further narrowed down which may be of interest to those really interested in their paternal line. If you want everything for one price with basic haplogroup information, then 23andMe is your better option.

Deep ancestry is not really my interest or specialism, but I found the forums and specific interest groups on FamilyTreeDNA really helpful. I did get the Big Y for my father, but only to try and narrow down the clues of where his paternal line should be from. I’m glad I did it for the interest value, and it enabled volunteers to find a new subset of my father’s haplogroup but it furthered my search in no way whatsoever; in reality, I should have just waited for more people to test through autosomal DNA testing.

I’m interested in health stuff but don’t really care about Ancestry

The best option for you is 23andMe. This will provide you with ethnicity information, and its DNA relatives feature, but you can opt out of the latter if you really don’t want to know who your relatives are.

There is another option of taking your raw DNA to a service called Promethease, but I don’t recommend this for the layman, particularly if you have any hypochondriac bent at all. The results kind of look like you are going to get every disease going if you don’t know how to read them! 23andMe is very clear about only allowing you to see specific results for specific things if you wish to see them, which is why I recommend that over Promethease.

 Since I originally wrote this article, the other genealogy companies have got in on the health stuff – LivingDNA, My Heritage and Ancestry US now also offer a DNA health analysis as well as the genealogy/ethnicity options.

I just want to know my ethnicity breakdown, I don’t really care about searching for biological family

If you are looking to find out ethnicity, family information within the past few generations, then an autosomal test (also known as atDNA) is what you will want, and there a few different companies which offer this test, Ancestry, FamilyTreeDNA, 23andMe, My Heritage, and LivingDNA. If you’re just interested in ethnicity it doesn’t really matter which you choose, although if you have known British ancestry you may wish to choose LivingDNA, who specialise in breaking down your DNA to specific areas of the UK. If you’re interested in health as well, then choose 23andMe (who will provide just ancestry, or health and DNA relatives as well, depending on which option you choose).


Note with all of these companies you can opt out of their version of DNA matching should you wish to; this means you won’t see your relatives and your relatives won’t see you.


If you just want to know your ethnicity, know that your results (spoiler alert!) are going to tell you that you are 100% human. If you are white and of British or Western European ancestry, your results are likely going to tell you that you are close to 100% European. If you’re a race other than white, your results are likely going to tell you have more European ancestry than you might expect, which can be difficult for some people to come to terms with, particularly those who know they descend from slavery.

No testing company is likely to agree on your exact ethnicity, and because the science on this is still relatively in its infancy, I would take any results with a pinch of salt. For example, here are my current ethnicity breakdowns according to the four major DNA testing companies (as at September 2018 – the companies amend their estimates as they get more reference samples to work with):


FamilyTreeDNA (in case you were wondering, the 1% is marked as South East European)

My Heritage



Other than the overall percentage, none of these appear totally accurate to me, but I do have a couple of unknown branches. On my original Ancestry ethnicity breakdown, I was dumbfounded by a large Western European percentage and assumed it was probably just British marked incorrectly. In fact, when I answered my own particular DNA mystery I found a strong Dutch heritage which suddenly made that percentage make a bit more sense. This is how my breakdown looks on traditional genealogy, I’ve based this on the known ethnicity of my 3x great-grandparents, this being the furthest away generation that I have the most data for (for two of those relatives I’ve taken the 4x great-grandparent ethnicities where I know this was different):



As you can see, none of the estimates from my DNA really match that, but it’s important to note that on the above I’ve calculated ethnicities mathematically, not genetically – I’ve assumed that my parents contributed 50% of my DNA (true genetically as well); made up of 50% of their parents etc, meaning the mathematical contribution of each of my 32 3x great grandparents would be 3.125%. In reality, due to the way DNA recombines to form in each person, the genetic makeup would not reflect my mathematical figures since I may have inherited no DNA from some of my 3x great grandparents or more than 3.125%.


The above images show several different possibilities for my ethnicity purely based on how each company defines its reference samples. At the moment DNA ethnicity estimates can only be treated as just that – estimates.

If you are of mixed race, Eastern European, Jewish African, Asian, Native American, South American, Middle Eastern or Pacific Islander descent, or have reason to believe one of those races may appear in your results, your breakdown may be more interesting than mine, and if you know one side of your tree is a certain race, the breakdown may give clues as to the other side. For example, one person I assisted to try and solve her mystery learned that her father likely had strong Eastern European roots, since her ethnicity profile very clearly showed a major Eastern European percentage; her mother’s results showed none.

I am looking for birth parents (mother/father/both), or I am hoping to solve a brick wall or mystery at grandparent/great-grandparent etc level.

Autosomal testing is the right test for you, so the previous advice applies with the caveat that, the further back the mystery is, means you may not be able to solve it with DNA. This is due to the way DNA recombines to get to you, and how much DNA from the common ancestor was inherited by you, and by your cousins. I have successfully solved mysteries at great-grandparent level for myself and others, I have not yet successfully solved a mystery at great-great-grandparent level; this does not mean it isn’t possible. I certainly found my answer by successfully finding common ancestors at the great-great-grandparent level and found DNA matches with common ancestors only at the 3x, 4x and even 5x level as well.

As far as the best test to take then the flippant answer is to test in the place where you will find your answers! Of course, this is the unanswerable question; you don’t know ahead of time where you will find your answers. However, you can hedge your bets a little here, read on!

6 – What should my strategy be if I’m searching for birth family/biological ancestors?

The reality is that you may have to test everywhere (or at least available upload your test results in as many places as possible), and this may still not lead to answers. But there is a way to maximise your chances.

My number one suggestion is to test at Ancestry first. The reason for this is because Ancestry currently (as at September 2018) has the largest DNA database of all the autosomal testing companies. According to this article, as at February 2018 Ancestry had tested over seven million people. Its closest competitor, 23andMe, had tested more than three million people.

My Heritage launched their service later than the others, in late 2016, but reportedly had sold more than a million testing kits by early 2018, and my suspicion is that this site will become a serious contender quickly due to its ‘Smart Matching‘ integration which works similarly to Ancestry’s hints function. FamilyTreeDNA does not appear to currently publish how many have used its Family Finder test but it’s believed to be in the low millions.

You can also download your raw data from Ancestry, 23andMe, and My Heritage to FamilyTreeDNA to see if any further matches show up there, but you cannot do this the other way round with Ancestry and 23andMe (My Heritage does currently accept raw data uploads which will be free until 1 December 2018). This means the most cost effective way to test to find biological family is:


1 – Test at Ancestry current costs US $99 / UK £79 plus postage, less if there is a sale running. This offers you the most chance of finding DNA matches. To check if you can buy an Ancestry test in your specific country, check this page.

2 – If no close matches/clues appear, download your raw data and upload it to:

  • FamilyTreeDNA (free to upload and view your matches, a cost of US $19 to unlock all Family Finder features, including the Chromosome Browser which can prove very useful)
  • My Heritage (free to upload until end of 2018)
  • If you choose you can also upload it to the volunteer-run Gedmatch or Gedmatch Genesis service which will enable you to see matches with those who have tested at other test companies if they have also uploaded their data to Gedmatch.

3 – If still no clues appear, as a final step you can choose to test with 23andMe; currently US $99 / UK £79 for just ancestry info or US $199/ UK £149 for health info and ancestry. They also occasionally offer sales and offer a discount for multiple tests ordered together.

7 – Be Prepared for a total lack of reply from your DNA matches should you choose to contact them

The truth is, a lot of people who DNA test are just not interested in responding, or finding out about their family history.  Some may have passed away, or have lost interest in their family history, or they were just bought the kit as a gift. Some may simply not know their family history and choose not to respond as a consequence. This is something you need to be prepared for, and also to mitigate against.

Brianne Kirkpatrick has an excellent post at her site, Watershed DNA, with draft language to use in contacting matches.

8 – Know that answers will not just be provided on a plate.

Unless you are one of the rare lucky(?!) ones who logs into their test results for the first time to see their closest match is a birth parent or very close relative, you should know that a certain amount of research is involved with working out exactly how a specific DNA match is connected to you, unless that match has shared their family tree with you, or it is at least identifiable from the information they have given. For that reason:

9 – Gather as much information as you can about your family history before you get your results.

If you’re an adoptee this may be nothing and that’s okay. But if you can get hold of your adoption record or your birth certificate, depending on where you were born may give as much as your mother’s name or as little as your birth date and place of birth. It’s beyond the scope of this website to go into detail here, suffice to say that the information available to adoptees depends very much on whether the adoption was open or closed, and the specific laws in place where you were born.

If you are able to glean some information, this will enable you to build as much of your family tree out as possible, using traditional genealogy research, which means when your results come through you may quickly be able to work out where matches are to specific lines in your tree, so know which matches to concentrate on to find answers to your specific questions.


10 – Take what you are told with a piece of salt

What you are told about your background, or a specific family story may be 100% true. It may be 100% false. In my case I had a specific name, a possible specific town, and the fact the person I was searching for was American. Of those facts, only one proved true, that he was American. Had I fixated on the name I was looking for, and the area of the US he was supposed to be from, I would still be searching now. It can be misleading to try and prove or disprove a story, so my best advice in trying to find your roots is to follow the DNA and see where it leads to.


So those are my recommendations for things to think about before you DNA test; if you’ve DNA tested, what would you want to tell people?  If you haven’t DNA tested but are thinking about it, what are some questions you have or things you are worried about?  Let me know in the comments!


NOTE: My opinion as to the best test to take for your circumstance is simply that – my opinion. I was not paid or sponsored by any of the test companies for this post.