I suspect a percentage estimate could be calculated for the likelihood of there NOT being shared ancestry when your matches on a particular 7+cM segment also all match each other on that segment. I would guess that it is less than one percent. This formula should include a variable for endogamy. I believe automated phasing is the ideal method. However very few people have the time or skill to use current procedures and tools. I contend that in the large majority of cases, you share a specific ancestral branch with your matches who all match each other on a specific atDNA segment measuring 7cM or greater. Sincerely, Peter Peter J. Roberts ****Please include this message in any replies****