Creating a Research Tree

One tree is all you need
  • Keep all your workings within one private and unsearchable Research Tree.  
  • Don’t start lots of separate trees – eventually you want to be able to join all the information you’ve gathered together within one tree that reflects all the branches of your DNA family.
Mirror Trees
  • You may find Mirror Trees suggested as a way of solving searches.
  • This technique is no longer the most effective way of working with your Ancestry DNA results – identifying groups of Shared Matches; Significant Ancestors within these groups and creating/connecting Floating Branches by tree building is a far more successful approach.
  • The term Mirror Tree is still popular – and often used when people really mean Research Tree. If you’re interested in the history of mirror trees, scroll to the end of this page.

How do Research Trees work?

Most people research their family history by starting a tree with themselves, adding details about their parents, their grandparents and continuing to add more and more generations, working back into the past.

If you don’t have any information about your parent(s) it is impossible to follow the same process! 

Research Trees work the other way round – instead of building information from the present to the past, a Research Tree starts with any distant ancestors you can identify and then you research their children, grandchildren etc to build the tree towards the present day. 



How do I get started?

Floating Branches
  • Your Research Tree will consist of many Floating Branches – “mini-trees” based on information gathered about your matches – see here for further information on adding Floating Branches to your Research Tree.   You don’t need to know out where you belong within the tree to start with.
  • If you keep researching and expanding each Floating Branch it should (in theory!) be possible to join the branches together and discover how your matches are related. 
  • I’m going to use the example of Bob and Mary and their family.  You are working on a Shared Match Group and, having built several Floating Branches, you realise that several matches have Bob and Mary as their Direct Line Ancestors:
  • You can bring this information together within your Research Tree by merging the duplicated people, which will connect several very small branches into a larger Floating Branch:

Once you know how your matches are related to each other, it is easier to look at the amount of DNA you share with each match and work out where you might belong within the Research Tree.

Who are my Direct Line Ancestors and how can I identify them?
  • Your Direct Line Ancestors will be ancestors such as your Grandparents, Great-Grandparents etc.
  • These ancestors will also be Direct Line Ancestors for your DNA Matches.  
  • You could be related to your DNA Matches in many ways, but for example:
  • When you work on a Shared Match Group, the first step is to identify “Significant Ancestors”.  These people are Direct Line Ancestors to several of your DNA Matches – like Bob and Mary in the example above. 
  • Significant Ancestors may also be your Direct Line Ancestors, or they may be a clue as to which direction your research needs to take to find them.
Do I have to type all these details into my Research Tree?
  • You can build trees however you wish – you may have to type some of the information in yourself, but you may be able to add other hints/facts from records such as census returns. 
  • To be able to build a Research Tree you will need access to the trees of your matches, and historical records, so it is very difficult to do without an Ancestry subscription.
  • It is possible to copy people from one tree to another (see Ancestry’s Support Guide here: https://support.ancestry.com/s/article/Copying-People-from-Trees). 

    However, if you are fortunate enough to have very close matches, you might want to avoid copying information directly from their tree into your Research Tree. If your match notices what you’re doing they may become curious and contact you before you are ready to discuss how the two of you might be related! 

Sometimes you build Floating Branches and find that one match within the group has a tree that is completely different to all the others – different names, different locations.  Some thoughts on why a match might not fit where you expect within a Shared Match Group can be found here.

For ideas on how to put the final pieces of your search together, click here.


You can open/save a pdf version of this document here:




Click here to return to the Free Resources page



Mirror Trees – a brief history…

What were Mirror Trees?

Mirror Trees were developed at a time when Ancestry had a much smaller DNA database and did not offer any information about Shared Matches.  The technique involved:

  • Recreating the tree of a close match
  • Attaching your DNA to someone within that tree (so you were deliberately attaching DNA to the wrong person)
  • In theory, this would generate Shared Ancestor Hints, which would help you identify which branch of the match’s tree was relevant to you
  • If you repeated this technique for enough matches you could identify several relevant branches, then try to work out how the branches connected to each other and where you belonged within the tree

Why have they fallen out of favour?

  • Each new “mirror” tree required you to unlink your DNA from one person and link it to someone else.
  • Ancestry then had to re-index all the information about your DNA, the Mirror Tree and the relationships to other matches with trees so Shared Ancestor Hints could be generated. 
  • Shared Ancestor Hints used to take a couple of hours or perhaps a day to appear, but as the database grew it took weeks/months.  By the time the Shared Ancestor Hints had been generated you could have found the same information by creating a Research Tree!
  • Mirror Trees should always have been set as private/unsearchable.  Unfortunately, this didn’t always happen, which led to other people receiving hints that incorrectly suggested they had surprisingly close family members.