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Exploring DNA Matches

Dan Kastrul’s recent presentation focused on concrete steps people could take to help make more sense of their DNA matches. He recommended uploading one’s raw DNA results to Gedmatch and learning more about the tools available on Gedmatch, including tools which help one assess if a match is due to chance or to inheritance. Gedmatch provides a way to reach a broader universe of those who may have tested at other companies than you did. Once you create a login and password you will find information on how to upload results. Among the tools he suggested were One to Many Comparisons and One to One Autosomal DNA Comparisons. These are some of the tools that are available for free. Dan makes use of Tier One tools which cost $10/month but allow you to go deeper into comparisons.


Three key concepts are important to better understand DNA matches. Those concepts are endogamy, uneven DNA split, and DNA triangulations. Endogomy results when there are marriages within a limited community. In many cases there were marriages between cousins in Jewish communities which results in multiple linkages and sometimes a higher level of centimorgans.  Dan used two decks of cards to illustrate how DNA divisions even between siblings can be quite divergent with each sibling receiving a different cut of the deck. DNA triangulation looks at three individuals who all share specific segments of DNA as a means to identify common ancestors. 


We covered different types of DNA tests, haplogroups, and cousin relationships. Dan also reviewed the importance of centiMorgans (cM) in understanding DNA matches and provided detailed information regarding how cM counts correspond to specific cousin relationships. A centimorgan is the measure used for measuring genetic connection. Dan also considered how to apply information about X matches to identify relationship pathways. He stressed the importance of having a family tree attached to DNA results and the importance of keeping trees updated to the present, e.g., identifying children of second cousins and their growing families. He also emphasized the importance of having as many known cousins, especially close, but also more distant, test their DNA as well as upload their results to Gedmatch. Dan concluded by providing participants with online data bases they could use to help find people, as well as additional online resources for further exploring this topic. e.g., online tutorials, blogs, and groups.



While the list is lengthy, here are just a few to get you started. There two Facebook pages specific to DNA. Check out Jewish DNA for Genetic Genealogy and Family Research, also Gedmatch Genealogy and Ancestry Group. There are also many blogs that address DNA analysis, among them one by Kitty Cooper. You may also want to check out the Genetic Genealogist.

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