Two good resources I don't see mentioned:
Blaine Bettinger's book is an excellent intro/overview, although it doesn't really address endogamy: https://www.amazon.com/Family-Guide-Testing-Genetic-Genealogy/dp/1440300577/ref=asc_df_1440300577/?tag=hyprod-20&linkCode=df0&hvadid=366402441998&hvpos=&hvnetw=g&hvrand=18258362118990958123&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9007906&hvtargid=pla-799253516361&psc=1&tag=&ref=&adgrpid=79033900551&hvpone=&hvptwo=&hvadid=366402441998&hvpos=&hvnetw=g&hvrand=18258362118990958123&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9007906&hvtargid=pla-799253516361

And the Jewish DNA group on Facebook (of which I am the administrator)
https://www.facebook.com/groups/DNAHelpJewishJourney



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Jennifer Mendelsohn
Baltimore, Maryland
https://www.apgen.org/profiles/jennifer-mendelsohn