So, You've decided to do a DNA Test ...
What's Next ?
There are MANY reasons for doing a DNA test:
- it was a birthday gift or similar
- to solve a family mystery
- to confirm or discount an old family story or myth
- to find out the ethnicity / background of your ancestors
- to identify birth parents or trace relatives who were adopted
- to track down lost or unknown cousins
- as a genealogy tool to extend and confirm the details in your family tree
Whatever your reasons, you may find the results difficult to understand, and not know how to proceed. This is where a DNA pack can help. We can take you through the process of organising a DNA test, and interpreting the results when they arrive.
Depending on what you are looking for, this could involve:
- ordering a DNA test (if you have not yet taken one)
- downloading your DNA and uploading to other databases
- reviewing your DNA matches and identifying clusters or related groups with shared DNA
- researching the family trees of significant DNA matches
- chromosome analysis to identify your most recent common ancestor (MCRA)
For ethnicity estimates, your DNA is compared to the DNA from reference populations that each testing company has developed.
To make their reference populations, DNA companies find people whose ancestry comes from a single location and avoid including individuals whose ancestry comes from several different geographies. The initial criteria generally used to identify candidates for a reference panel is that all four grandparents originate from the same non-colonial geography (not USA, Australia, etc). DNA companies also survey participants for trans-national identifications that are important for distinct ethnicities that can form their own genetic populations separate from geography of origin (i.e., Ashkenazi Jewish, Cherokee, Basque and others). As each company has their own reference panels, results may differ depending on whether your test is from Ancestry, FamilyTree DNA, 23&Me etc.
Also, these reference panels are continually being updated and getting more granular as new distinct ancestral populations are being described, so your ethnicity results may change over time as new updates are released. Your DNA does not change, but the science behind it does, enabling us to get more detailed and accurate results at each new release. Note that you are not charged when a new update is made – you are free to log in to your DNA testing site and see your updated results at any time.
As an example, the test below is the same individual, originally tested in 2018, along with the ethnicity estimates updated in 2020 and 2022:
You can also download your DNA from the original testing company and upload to other companies, without having to do another DNA test. This allows you to take advantage of matching your DNA with others who may not have used the same original testing company. It also means you can compare your ethnicity estimate against a difference reference database. In this example, the same DNA that was in the above 3 ancestry results was uploaded to Family Tree DNA and produced the following ethnicity estimate:
With the autosomal DNA test, you also receive a list of your DNA matches based on the amout of DNA you share with other people who have done the test.
This list will obviously be biased by the countries in which the test is available, and the number of people who have taken a test. The good thing is, that once you have taken a test, new matches are added to your list continually, so even if you have very few matches when you first get results, these are constantly updated.
As you only inherit 50% of DNA from each of your parents, the amount you share is diluted every generation. Some testing companies report the amount of DNA shared in percentages (eg. 23andMe), however most report the amount of shared DNA in centiMorgans (cM)
A likely relationship to you is estimated based on the amount of DNA shared (measured in centimorgans (cM). On average, you share about 3485cM with a parent, 2613cM with a sibling, 1754cM with a grandparent, 866cM with a first cousin etc. The relationships mentioned on the report are just an example of what the link could be, but we can help explore other possibilities.
Of course, when you inherit DNA from your parents, it is not EXACTLY 50%, and there can be some variation at each generation. Based on actual DNA measurement, the chart below shows the range of shared DNA in cM that is shared amongst cousins. Your match list will include the amount of DNA shared in cM as well as a possible relationship (eg. 3rd cousin), however as you can see from the chart below, there is considerable variation and overlap in the amount of DNA shared by different relationships, thus other genealogical methods need to be used to accurately determine the relationship of your DNA match. Again, this is something we can help you with as part of the DNA pack.
You can also find out which of your matches are shared with other matches, so if you recognise one of your matches, or can persuade another relative to also do a test, this will enable you to work out if a match is on the maternal or paternal side ….. or even a particular branch of the family and Ancestry provides some useful tools to allow you to create your own categories and groupings to organise your matches.
If you have an online family tree with Ancestry, it will also compare the trees uploaded by your matches with your own tree and see if there are any overlaps. This is an incredibly useful tool that allows you to not only grow your own tree, but also to accurately identify where your DNA matches fit. We can certainly help you get started with this analysis.
If you’re interested in a more advanced analysis of your DNA matches in order to determine most recent common ancestor (MCRA), or are trying to identify birth parents in case of adoptees, a bespoke service can be arranged. Genetic genealogy involves a detailed analysis of shared DNA segments at the individual chromosome level to prove a relationship. Even though DNA is shared with your DNA matches, this is only suggestive of a particular relationship, especially when small amounts of DNA are involved. It may be that the shared DNA is from a different ancestor which you have not considered, thus to determine an definite relationship, we need to show that the identical section of DNA on a specific chromosome has been passed down the generations.
This may involve downloading your DNA from ancestry, and uploading it to MyHeritage or GEDMATCH (as ancestry does not provide details of chromosome segments shared). If appropriate, some additional DNA tests to identify deep paternal ancestry (Y-DNA) – ie DNA passed down from your fathers, fathers father etc. or mitochondrial DNA (passed down intact from your mother’s mother’s mother etc.) can be taken.
As Y-DNA is passed down intact from father to son, this test may be used to identify a potential birth father’s surname. It is highly dependent on the number of people who have previously taken the test, however for adoptees, this could be the one thing that breaks through their brick wall leading up to identification of birth parents.
The above screenshot shows the case where a particular section of DNA on chromosome 10 is an exact match between 3 DNA matches – this confirms that these 3 individuals inherited this section of DNA from a common ancestor.