HAYDEN YDNA PROJECT – Background

My interest in genealogy didn’t start until I was in my early 50s. Researchers of my maternal line had spent many years searching for the father of my greatgrandfather who had been a federal soldier in the Civil War. This greatgrandfather had kept a detailed diary but, unfortunately, it contained few clues about his father. I got hooked and started to search the internet for any information. In this way, on a forum board, I met a 2^nd cousin once removed and her husband. Under their leadership and guidance, I learned about Y-chromosome DNA and how it could help break through the “brick walls”. And, it did break the wall and that line is now traced back to County Tyrone, Ireland.

In the meantime, I became curious about my paternal, Hayden, line. I had family records of my Hayden line back 4 generations to when they left Missouri and immigrated to Oregon. I was able to obtain census, birth, marriage and death records for these four generations. But, I hit the “brick wall’ going any further back. This seemed like a Y-chromosome candidate study to me. Hence, I started the Hayden Family Y-Chromosome Project with FamilyTreeDNA. The “brick wall”came tumbling down and I found many cousins I never knew anything about. This work continues.

Inaddition to finding Haydens of my line, I found alternate spellings such as Haydon, Haden, Heydon, Hyden, Hadden and so on who joined the project. Also, some members have different surnames indicating a non-paternity event. As the number of members of the project increased, it became apparent that there are,at least, three Hayden lines in America who do not share a common Hayden male ancestor in a genealogical time frame. In addition, there are, at least, 3 Haden lines not related to each other or to any of the three English Hayden lines.Additionally, several Irish “Haydens” have joined the project. These “Haydens”do not appear to be related to each other or to the English Hayden lines. More about this in the Results section of this site.

Y-Chromosome Testing “Dumbed Down”

Imake no claim to have expertise in genetic DNA. I do have considerableexperience in applied statistics which is helpful in understanding Y-chromosometest results. Here’s a really basic version of Y-chromosome testing and analysesmethods.

We have 23 pairs of DNA in most of our body’s cells. One of each pair is inherited from our mother and one from our father. The 23^rd pair is called the “sex pair” This pair contains either two X-chromosomes in the case of females or one X and one Y chromosome in males. So, the Y-chromosome in males is inherited from the father. Because of this, the Y-chromosome can be used to trace the male line back for generations.

In genetic testing, locations on the Y-chromosome, designated by a DYS#, often called markers, are measured. The numbers at each DYS# you see in your report, called alleles, are a measure of the number of repeats of specific units of DNA bases at that DYS# site. The number of repeats (alleles) can change at a generation change. That is, a mutation occurs. The estimated average mutationrate quoted in the literature varies from about 1 in 500 generation to 1 in 250generations. One can then count up the number of mutations of one test subject compared to another. This number is call Genetic Distance, or GD. Then using the GD and an average mutation rate, one can estimate the generations back to the earliest common male ancestor. Things do get a bit more complicated when one considers the fact that the mutation rate is a function of the marker. Fortunately, FamilyTreeDNA has an app, called TiP, which takes this into account to estimate the number of generations to the earliest common male ancestor.

Both the GD and TiP apps are available on your FamilyTreeDNA home page allowing you to compare your Y-Chromosome results with another project member. Clearly, these calculations can only be made for the markers both test subjects have incommon. This means, for example, if you tested at 111 markers (Y-DNA111) to someone who tested at 37 Markers (Y-DNA37), only the first 37 markers of the Y-DNA111 test result can be used to estimate the generations to the earliest common male ancestor.

The TiP app uses GD as a function of marker DYS# to calculate the probability that the earliest male ancestor occurred with a certain number of generations. “Probability” is the key word here. TiP doesn’t tell you how many generations to the common ancestor but gives an estimate. The confidence in this estimateis is a function of the number of markers, sample size, used in the calculation. That means, if you want the best estimate possible, you need to compare Y-DNA111 test results for both test members. It also means that Y-DNA12 tests results provide estimates with which one can have only low confidence. This is why in FamilyTreeDNA GD calculations there is maximum GD result reported. The maximums are as follows:

Y-DNA12: 3

Y-DNA25: 5

YY-DNY37: 7

Y-DNA67: 25

Y-DNA111: 40.

This is why I recommend, as a minimum, the Y-DNA67 test.

This, of course, doesn’t answer the question “at what probability should one pursue further research”?  There is no right answer. It all depends on how much effort and cost one is willing to expend to achieve the probable reward.