My point was: some have segments as long as 20 cM some as short as ~7.  Of the 30 or so, about 20 have each other on that segment and if they don't, it's because the one stops at 10 say and the other starts at 10.  And even for the pairing which they don't  have on c 18 (because of the start stop at 10 effect), many have matches elsewhere.  And they're all matches to me.  And I have the least ancestry from close to the epicenter of their genealogies (mine is about 300 miles).