07 July 2010

Family Finder Testing Series: Expanding the matches; narrowing the search

Testing with the Family Finder test or other similar autosomal test can easily lead to hundreds of matches, giving us a multitude of cousins. However, with this test, the difficulty lies in finding where the common ancestor is on our pedigree chart. Although this type of testing is in its infancy, genealogists are greatly interested in increasing the number of matches, and they are scrambling to find easy ways of locating the common ancestor. Over time, more methods may develop, but for now, these can help.

Expanding the number of matches

As genealogists, we know that the more people you contact, the more likely you are to find someone with the information you are missing. The more cousins you match, the greater the possibility of adding more generations to your lineage. However, there are only two ways to expand the number of matches you have; either have people in your family test or wait for matches to appear on your website. The greater advantage is to have family members test.

Since each person inherits a different mix of DNA from their ancestors and since a minimum length of DNA is required to determine a match, testing more family members will result in more cousin matches. Many of your cousins may have already tested, but as you did not inherit enough of the same DNA segment, you will not match them. Your relatives may, however.

All of us are not fortunate enough to have the following list of relatives to test, but for each that you can test you are more likely to find additional matches. Every family member has inherited different DNA from the ancestors and will, therefore, match other testers.

· Parents and grandparents.
· Siblings of the parents and grandparents.
· Your siblings.
· First, second, and third cousins.

Not only will the above list increase the number of matches you can have on Family Finder, but testing these relatives will also help you more easily locate the common ancestor between you and your match.

Narrowing the search for the common ancestor

Finding a common ancestor given all the thousands of names we may have in our database can be daunting. Where do you begin? How can the hunt be narrowed to something manageable?

After determining the time period or range of ancestors where you are most likely to match your new cousin as outlined in the previous article Sharing Your Genealogy Research, you may wish to take an additional approach to reduce the amount of searching required in order to find that common ancestor. As each of us inherits different lengths of DNA segments from our ancestors, testing multiple family members can help you focus on which lineages you may have in common with a match. Although nothing is fool-proof, these ideas that can help you determine where to begin looking and improve your success rate for finding the common ancestor.

Testing Older Generations

Testing older generations is helpful because it narrows your search to fewer branches of your tree. When you and a grandparent match the same person you narrow your genealogical search to that grandparent’s line.

When your parents and grandparents are not available you may also test their siblings. Unlike testing your direct line though, you cannot use an aunt, uncle, great aunt, or great uncle to rule out a line. This is because they may have inherited different DNA from their parents.

Testing the older generations means you can find matches farther back on your lines as parents and grandparents have longer segments of ancestral DNA. A match with a grandparent will help you focus on particular lines to find the common ancestor. Again, these family members would have longer links than you would have for older generations, and the siblings would have inherited different mixes of the ancestors’ DNA, giving you other matches.

Testing Cousins

Testing cousins is a way to clarify which side of your family you share with your match. Unlike testing older generations it cannot be used to exclude a line, however. When you match someone, but a tested cousin does not, you may or may not be able to rule out that line for reasons beyond the scope of this article, but know that if your match matches a cousin you can narrow your search to that those related lines.

Testing first cousins on your father’s line as well as your mother’s line could determine which half of your lineage is related to your match. If your match shares a DNA segment with your maternal cousin, then all three of you share ancestry from your maternal line.

If you can only test one of the cousins, for example a son of your father’s brother, you can still benefit. If that cousin, you, and your match share the same DNA segment in the same location on the same chromosome, then the common ancestor is on your father’s line.

Again, the opposite is not always true. If your match does not have the same DNA segment with your paternal cousin, the possibility is that either the common ancestor is on your maternal side or your paternal cousin did not inherit enough DNA to be above the minimum amount needed to be declared a cousin. This can happen if the match is more distant than a first or second cousin. In these cases, the match could actually be on either parent’s line. Testing additional cousins may help as other cousins could have inherited enough of the DNA from that ancestor.

Testing second and third cousins is greatly beneficial as these relatives give you DNA segments you may not have. You can also narrow your search based on how those cousins are related to you.

In summary

1. Test older generations to include or exclude the main branches of your tree.
2. Test cousins on your paternal and maternal sides to determine which half of your lineage could hold the common ancestor.
3. Remember that if a relative does not match your matches, it means they did not inherit a long enough segment of the common ancestor’s DNA.

In posting my success stories for DNA testing on this blog and in discussions with others I know who have tested with Family Finder, I have found cousins who do not match me on my autosomal test. As stated, this is because both of us did not inherit enough of the same DNA segment. We have the same lineages and those lineages have been confirmed as accurate since other cousins did match me on those lines. In this way, autosomal testing gives great confidence to our genealogical paper trails as well as help us find new cousins with whom to research.

copyright: E. Aulicino, July 2010
Thank you R.

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