An Extraordinary Advance in Y-DNA Research

An Extraordinary Advance in Y-DNA Research

Those who have followed the genealogy research on this blog and in my book, The Wathens of Southern Maryland: Their Genealogy & History, know that Y-DNA testing is a powerful tool for tracing your male ancestry. Through Y-DNA tests from Family Tree DNA, I was able to figure out how two of the three local branches of Wathens were connected to one another and to the colonial settler John Wathen. There is still some uncertainty about how the third branch - that of James Hanson Wathen - fits in the Wathen family tree, but I have hope that the mystery will one day be solved.

As I explain in greater detail in my book, the Y chromosome is a string of over 60 million letters of genetic code that is copied and passed down from father to son, generation after generation. Occassionally copying errors occur, changing a single letter of genetic code from previous generations. These mutations, called single nucleotide polymorphisms (SNPs), are then passed down to all future generations, helping us to distinguish one branch of a family tree from another. To put it very simply, comparing and contrasting letters of DNA code on the Y chromosome is the key to figuring out how different men are genetically related in the male line.

The most widely used commercial Y-DNA test is Family Tree DNA's Big Y-700 test, which was released in 2019. At the time, scientists could not figure out how to access and decode a large section of the Y chromosome. The Big Y-700, therefore, can sequence only about 23 million letters of genetic code - less than 50% of the Y chromosome. This image from Family Tree DNA from 2019 shows how much has remained inaccessible:

There's a good chance that some of that unaccessed DNA code could contain information that is helpful to genealogists. Could SNPs in that unexplored region help to demonstrate how James Hanson Wathen is connected to the rest of the Wathen family tree?

Answers may soon be possible.

Researchers led by the National Human Genome Research Institute (NHGRI) recently published information about an exciting breakthrough: Scientists have now discovered how to sequence 100% of the Y chromosome! It will probably still be a while before full sequencing is available commercially through companies like Family Tree DNA, but more advanced testing is no doubt on the horizon. What new information about the Wathen family tree may be in that previously-inaccessible sequence of DNA?

Reminder: Use the discount code WATHENDAY through September 16, 2023 for $5 off of printed copies of The Wathens of Southern Maryland: Their Genealogy & History.

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