Have you ever wanted to trace an ancestor who has eluded your paper research, and wondered whether DNA could help? This month, Karen Evans takes us through her tried-and-tested strategies for putting DNA to work

One of the major reasons people take a DNA test is to find a ‘missing’ ancestor. It may be that they have no knowledge of their family due to adoption or were brought up by a single parent with no information about their unknown father or mother. Perhaps in your family history research you have uncovered an illegitimate ancestor and want to find out who was the daddy! But how likely is it that DNA will help you uncover those potential brick walls?

The truth is … it’s difficult to know. There are several factors that can have a positive or negative effect on your chances of success. I’m going to show you how I approached some missing ancestor searches I’ve been involved in, and some of the tips and tricks I use to find that elusive unknown.

Whether it’s a missing mother or an unknown great-grandfather, there are several steps in common. All of them are looking for evidence (either genetic or paper) that points to a likely suspect or suspects. These are the things we need to consider:

• Is there any information about the unknown ancestor: such as documents (for instance, a bastardy record or newspaper report), or anecdotal evidence (such as a surname used as a middle name, or a family story?).

What evidence can we find that points to an unknown ancestor?

• What do our DNA matches reveal?

• Can we place a suspect or suspects in the right place at the right time (geographical proximity)? Put simply: ‘Bert’ couldn’t have fathered your grandmother if he was serving overseas at the time and didn’t return home.

I’m going to be focusing on the DNA aspect of the search, but other non-DNA evidence will always play a part.

Plan of attack: Find the matches!

My aim is to focus in on the matches that ‘could’ represent a missing ancestor, but how to spot them amongst the hundreds, if not thousands of matches? I need to ‘remove’ the other matches by clustering. Below is a step-by-step guide of how to do this with a missing paternal grandfather, but the same technique will work for a missing closer or more distant ancestor. I call it ‘cluster, research, remove, repeat’. I’m using Ancestry in my example as it has the largest database with clear clustering tools.

How likely is it that DNA will help you uncover those potential brick walls? The truth is ... it’s difficult to know

Step 1: Cluster

On Ancestry you can see matches as ‘Parent 1’ and ‘Parent 2’ (known as Side View). This basically clusters your matches into two large groups – one for your paternal side, one for your maternal (even if your parents haven’t taken a DNA test).