Common Ancestors on Ancestry - an odd thing

[Gadget]

..and another one that she manages in which the tree is linked comes up as a Common Ancestor.  Maybe it's something to do with linked* trees 

* and unlinked

Add - I knew how this group were related to me and each other without looking at Common Ancestors

[LizzieL]

I went to thrulines from the main DNA sign in page. It gives each generation as a pink or blue icon (depending on gender) If you hover over each it says if there is a thruline associated and if you click, it shows up, the same as it would if I click common ancestor. As I haven't got as far back with some branches as others and there is some illegitimacy, not every generation of mine has a full set of ancestors, but now some potential ones in green have appeared to try to complete the set. One pair is right, just not updated my tree on Ancestry, one is impossible (unless my 3 x great grandfather fathered a child at age 6), but another pair are worth further investigation.

[Gadget]

I didn't mean the ThruLines via top right link. I meant going to your Common Ancestors listing, selecting the relevant match, then clicking on the left hand link that says View Relationship which is  under an ancestor. This takes you to a suggested relationship tree which then allows you to click on View Thrulines. This then displays al l the relatives that Ancestry sugests link to the common ancestor.

[Sinann]

If both father and son are the same 'home' person on the linked tree than the system most likely can only handle one of them, other wise it would have to put a home person as a Common Ancestor twice.

[GailB]

I have a match at 10 cM with CM (full name given on Ancestry). Ancestry has flagged it up as a Common Ancestor match. CM's surname is the same as one of my direct ancestors which I have researched reasonably well, so it was clear to see where our trees overlapped and confirm that he was my 5th cousin once removed. Our common ancestors were my 4 x great grandparents (and his 5 x great grandparents). CM manages the test for EM. My match with EM is at the same level and the tree attached to EM's results is the identical tree attached to CM's results, same size, same name, same home person. In fact if the tree was just called "M... family tree" instead of "CM's family tree", I wouldn't know which of the two people was the home person.
 
Both EM and CM appear on the tree (obviously as private). EM is CM's son, so he would be my 5th cousin 2 x removed
But I don't have a common ancestor match with EM according to Ancestry. Can anyone suggest why this should be?

Common Ancestors and ThruLines only show matches up to your 5x great grandparents. If you have a match that is 5C2R it won't show in Common Ancestors or ThruLines because it is too many generations.

[LizzieL]

I have a match at 10 cM with CM (full name given on Ancestry). Ancestry has flagged it up as a Common Ancestor match. CM's surname is the same as one of my direct ancestors which I have researched reasonably well, so it was clear to see where our trees overlapped and confirm that he was my 5th cousin once removed. Our common ancestors were my 4 x great grandparents (and his 5 x great grandparents). CM manages the test for EM. My match with EM is at the same level and the tree attached to EM's results is the identical tree attached to CM's results, same size, same name, same home person. In fact if the tree was just called "M... family tree" instead of "CM's family tree", I wouldn't know which of the two people was the home person.
 
Both EM and CM appear on the tree (obviously as private). EM is CM's son, so he would be my 5th cousin 2 x removed
But I don't have a common ancestor match with EM according to Ancestry. Can anyone suggest why this should be?

Common Ancestors and ThruLines only show matches up to your 5x great grandparents. If you have a match that is 5C2R it won't show in Common Ancestors or ThruLines because it is too many generations.

CM is my 5C1R - our shared ancestors are my 4 x great grandparents. CM's son is my 5C2R. Our shared ancestors are still my 4 x great grandparents. The number of generations on my side hasn't changed at all.

[GailB]

But your 4x great grandparents would be your 5C2Rs 6x great grandparents.

[LizzieL]

Yes, of course, so cousins descended from my 5 x great grandparents only show if they are also their  5 x great (or lower number of greats) grandparents. That's a nuisance, I'm descended from a much younger sibling at several points on my tree, so many distant cousins who are my age contemporaries or even older are a removed down.

[GailB]

Yes it is a nuisance. I have a few in exactly the same situation as you.

Gail