17 May 2015

Y-DNA or Who’s My Daddy?

By Emily Aulicino

In the past I have posted information about the various tests on this blog.  However, when I was approached my my local genealogical society, I submitted several articles to help members of the society with DNA testing.  I am most grateful to all those who helped compile many of the coming articles and who edited my work.  A special thanks to Laurel Smith, our current president, for pushing me to do this and for all her help.

In the coming weeks, I will cover mitochondrial testing in two parts, autosomal testing, SNP testing and a few other topics.  You may email me directly if there is a topic you would like clarified and posted here.  Do not post to the blog, but to me directly:  aulicino@hevanet.com

The following questions or goals may be addressed with the Y-DNA test. 
Although there are no guarantees of success, this is the mostly logical path to try. Each of these will be considered here:   
  •     Proving if a person is my father
  •     Finding biological father’s (grandfather’s, etc.) surname (adopted or not)
  •     Proving two of same surname living in adjoining towns are related
  •     Y-line brick wall, hoping to jump the brick wall
  •     Tracing mother’s father’s line back to a known immigrant

The Y-chromosome is passed from father to son virtually unchanged since mankind began. The small changes (mutations) that can take place help determine the closeness of a relationship and help place people into family groups. These mutations are random and can happen at any time. That is, a father could give one son a certain DNA result and another son the same, but perhaps with one mutation. Consequently once a mutation occurs it is passed to the next generation of sons from the father who received it.

As the Y-chromosome is only inherited by men, this test can be taken only by men. It tests the top line of a pedigree chart for a male tester. However, the results does not really belong to or indicate a particular male as all the males in the family and everywhere along a direct line of descent can have the exact same Y-DNA results. That is, a great-great-grandfather gives a copy of his Y-chromosome to all his sons, but so do that great-great-grandfather’s brothers give it to their sons. For this reason, it tests more than just the direct line of male descent, but all the direct male lines of that progenitor.

The result of a Y-chromosome DNA test yields a number for each marker. That number depends upon the number of times four chemical bases (adenine, cytosine, guanine, and thymine) repeat themselves in a short pattern. These patterns must repeat themselves right next to each other or in tandem and are referred to as an STR or short tandem repeat. For example a marker could have a pattern of AGAT or some other combination, and the number of times it repeats itself in sequence; for example, AGATAGATAGAT would result in the number for that marker. In this example, the result would be a 3. The result of a marker is called an allele. The entire test result is referred to as a haplotype. In the example below marker DYS393 has 13 STRs.

The alleles (marker results) are compared with those of other testers to give an indication how closely related they could be, but as DNA does not tell you the name of a common ancestor, you still need to do your genealogy. DNA testing can help you get through a brick wall, determine the surname of a person who is adopted, and prove that two males do or do not have a common ancestor in genealogical time. DNA testing gives you the names and from some companies the emails of the people with whom you share a common ancestor. This allows you to contact the matches and share genealogies. The more wide-spread your records are, the easier it is to find the common ancestor. That is, do not research just your direct lines, but everyone’s children, grandchildren, etc.

If you are a woman, you need to have a male in your father’s all male line do the testing; otherwise a man can test for his father’s line as I have said.

To prove if your father is your father, you should test yourself and your suspected father. If that cannot be done for some reason, test yourself and a male that either descends from your suspected father or from one of his brothers, given that you are certain of those relationships.

To obtain a man’s biological surname, just test the man and see what surname is most frequent among the matches. The odds are this would be the testers’ surname, barring any NPE (non-paternal event or any event that would result in a non-biological surname such as an adoption, illegitimate birth or a name change for any reason).

To determine a paternal great-grandfather (adopted or not), without knowing which of two people that could be, I’ll address both. If the paternal great-grandfather is your paternal grandfather’s father, then test yourself, if you are male, and see whom you match to get a surname. If the paternal great-grandfather is your paternal grandmother's father, then you need to find a brother of your paternal grandmother and bring his line down to the present in an all-male line. If this is confusing, look at a pedigree chart. The same system can be applied to the comment above about finding a great-great-grandfather.

Proving that two men with the same surname and living in nearby towns are related can be easily done. Just bring to the present the all-male lines from each of your target people. Test one person each and see if their test result matches. However, finding a viable candidate is often the problem. For this reason bring all the male lines to the present as some lines may “daughter-out” or some men may refuse to test or cannot be located.

Jumping a brick wall can be done, but there are different methods. One is to test a male and contact the matches, hoping someone has more information than you do. Another way is to check the area where your trail went cold to see if there are others in that area who may be related whom you cannot fit into your pedigree. Bring an all-male line to the present and test that living person. If there is a match, perhaps they know something you do not or together you and your match can research the line to see if you can track it back farther. Sometimes distant cousins leave better paper trails than your direct line. Lastly, you can triangulate a line. This method is a bit longer to explain, and will be covered in another lesson.

And for the last problem above, tracing mother's father’s line back to a known immigrant, use the Y-chromosome test. You must go back to the moth­er’s father, bring an all-male line to the present, and test that person. Then you must bring an all-male line from the known immigrant to the present and test them. This method was actually used to prove a Mayflower descendant a few years ago.

As you can see from all these examples there is great similarity in how to use the Y-chromosome DNA test. BUT, which Y-chromosome test? I recommend at least 37 markers as that number of markers puts your matches within genealogical time. After all, you need to have a paper trail along with the DNA to really prove your lineage. Of course, testing more markers is just fine, as well. Some people choose to start out with a 37 marker and upgrade later while others test the 67 or 111 initially. The cost of upgrading is a bit more than the difference between the two tests you choose. This is because the company has to locate your sample in their vaults.

Much of what you need to know is on my blog in the older sections. There are many articles you can skip as they are about my antics at conferences or on past sales. Also understand that over the years genetics has evolved so some things that were thought to be true a few years ago may be understood differently now, but the basics are the same.

I urge all of you who have not tested to write me before you order. I will ask you what problem you are trying to solve so I can be sure that the test and the company you choose will serve you well. I have had several emails from people who bought first and then inquired. They are not happy. Remember that DNA testing is becoming very popular and as a result there are many companies who want a slice of the pie, but they do not offer all the services that others do. It is wiser to not let price be your guide in most cases. Variety of testing, service, storage of your sample so you can upgrade later, etc. are only a few of the important features.

One last reminder: DNA testing does not have all the answers for you. Not every brick wall can be demolished; there will always be brick walls. Not every person you need to test can be found or, if so, they may elect not to test. Not every person you match will know as much as you. With luck, some will know more.

One last hope: DNA testing is the most accurate resource we have as genealogists. By testing you will have an opportunity to learn more about your ancestry. More people are learning about DNA testing for genealogy daily. More people test all the time so in the future you may find the person and connection you need. Doing nothing gets you nowhere.

Written for the GFO DNA Special Interest Group, 29 Jan 2013 and appeared in the GFO Bulletin, Volume 63, No. 3, Mar 2014. 

GFO is the Genealogical Forum of Oregon in Portland Oregon.  See their website:  www.gfo.org

Thank you,