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  • FTDNA vs Ancestey matches

    My son finally has another match on Ancestry. He doesn't seem to have many overall. This one just happens to be a suggested 3rd cousin. I'm guessing at least once removed since I believe the match is around my age. They share 146 cM across 7 segments. On FTDNA my sons closest match which he shares with me only shares 78 cM but is listed as a 2nd-4th cousin. I know there are differences in FTDNA and Ancestry. Just wondering how to tell the relationship range this one may be since there is such a difference in sites. FTDNA doesn't have any matches that share that much cM except his full sister and myself.

  • #2
    The key problem you have is that Ancestry does not have a chromosome browser.

    I suggest uploading your kits to the free site gedmatch.com. If your son's ancestry match also does that, you will have a basis for establishing the locations of these 7 common segments and their size. Ideally the close FTDNA relative would also upload for a direct comparison. Even if the FTDNA relative did not upload, you could still roughly determine if the common segments were the ones of interest.

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    • #3
      According to the ISOGG chart, 3rd cousins average 53 cM and 2nd cousins average 210.

      78cM at FTDNA is definitely in 3rd cousin range and FTDNA "plays it safe" by saying 2nd to 4th

      146 cM at AncestryDNA sounds more like 2nd cousin, once removed . The 146 has been phased downwards so the real is a bit higher but how much I can't say. AncestryDNA also plays it safe and wont call a 2nd cousin until 200 cM.

      But you might still be right about 3rd, once removed. I have a 3rd,1r at AncestryDNA who shows 127cM. According to ISOGG that would have been only 26. He shows 178 at GedMatch.

      So you should do what ECH says and load the data to GedMatch so you can see what is really happening.

      If your son's ancestry includes immigrants to North America recently ( after 1850) then that could explain some of his low matches. I am very Colonial and I have 11000 matches. But my wife is only 3rd generation US and she has very few matches.

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      • #4
        Thank you for posting this as I have been wondering the same thing. I too have very few matches with Ancestry - probably half of my FTDNA matches.

        Like you my largest match with FTDNA is 109 cm showing as 2nd to 4th cousin, but my 189 cm match with Ancestry shows as 3rd to 4th.

        The 189 cm match led me to my birth father (who unfortunately just passed), but also to a 1/2 brother & sister, who happen to live in the same city as me (but that is another story).

        Ancestry says my match and I share great great grandparents, but in actuality we share great grandparents as my grandfather and his grandfather were brothers.

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        • #5
          Originally posted by Sara291 View Post
          My son finally has another match on Ancestry. He doesn't seem to have many overall. This one just happens to be a suggested 3rd cousin. I'm guessing at least once removed since I believe the match is around my age. They share 146 cM across 7 segments. On FTDNA my sons closest match which he shares with me only shares 78 cM but is listed as a 2nd-4th cousin. I know there are differences in FTDNA and Ancestry. Just wondering how to tell the relationship range this one may be since there is such a difference in sites. FTDNA doesn't have any matches that share that much cM except his full sister and myself.
          Ancestry is often too conservative. Second cousin, once removed sounds quite possible for this 146 cM relationship, as would half-second cousin, or a few other combinations. But the fact is that the spread gets wider and wider as the relationship gets further.

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          • #6
            Originally posted by loisrp View Post
            Ancestry is often too conservative. Second cousin, once removed sounds quite possible for this 146 cM relationship, as would half-second cousin, or a few other combinations. But the fact is that the spread gets wider and wider as the relationship gets further.
            About 2 or 3 months ago, Ancestry recalculated everyone's matches with some sort of change in their algorithm. There have been complaints that their new algorithm was too conservative in some cases and downgraded their estimates from the previous estimate. I had two cases of this for close matches.

            A paper trail proven 2nd cousin was previously estimated correctly as a 2nd cousin. After the algorithm change, they downgraded him to a 3rd cousin estimate. We share 193 cM in 3 segments.

            A paper trail proven 3rd cousin was previously estimated correctly as a 3rd cousin. After the algorithm change, they downgraded him to an estimated 4th-6th cousin at the extremely high confidence level. We share 88 cM in 4 segments.

            For the purposes of comparison by the OP to her case, I have two paper trail proven 3rd cousins (brother and sister) who were estimated correctly by Ancestry as 3rd cousins. They're still estimated as 3rd cousins. I share 117 cM in 4 segments with one and 97 cM in 2 segments with the other.

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            • #7
              I am also very Colonial. I have more than 14,600 matches at Ancestry. The lowest match shares 6.0 cMs. They usually give me between 30-50 new matches each day. Yesterday, I got more than 100. Only 17 of those had trees.

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              • #8
                My mom has a confirmed paper trail 2nd cousin, their grandmother's were sisters, and this is how he shares with my mom at Ancestry vs. FTDNA:

                Ancestry:

                Predicted relationship: 3rd Cousins
                Possible range: 3rd - 4th cousins
                before recalc: 151 centimorgans shared across 12 DNA segments
                after recalc: 149 centimorgans shared across 9 DNA segments

                Same guy at FTDNA, I assume an Ancestry upload but I don't really know:

                2nd Cousin - 3rd Cousin
                166 shared cM
                32 longest block
                15 shared segments in the chromosome browser.

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                • #9
                  Originally posted by MMaddi View Post
                  About 2 or 3 months ago, Ancestry recalculated everyone's matches with some sort of change in their algorithm. There have been complaints that their new algorithm was too conservative in some cases and downgraded their estimates from the previous estimate. I had two cases of this for close matches.

                  A paper trail proven 2nd cousin was previously estimated correctly as a 2nd cousin. After the algorithm change, they downgraded him to a 3rd cousin estimate. We share 193 cM in 3 segments.

                  A paper trail proven 3rd cousin was previously estimated correctly as a 3rd cousin. After the algorithm change, they downgraded him to an estimated 4th-6th cousin at the extremely high confidence level. We share 88 cM in 4 segments.

                  For the purposes of comparison by the OP to her case, I have two paper trail proven 3rd cousins (brother and sister) who were estimated correctly by Ancestry as 3rd cousins. They're still estimated as 3rd cousins. I share 117 cM in 4 segments with one and 97 cM in 2 segments with the other.
                  These are the new AncestryDNA standards (partial chart from help page). They are not very aligned with ISOGG numbers, particularly since they have been phased downwards in terms of cM. So AncestryDNA is being very conservative.

                  200—620 2nd cousin ISOGG 212
                  90—180 3rd cousin ISOGG 53
                  20—85 4th cousin ISOGG 13

                  I am not sure how strict they are from 181 to 199 but based upon MMaddi's second cousin and my two second cousins (187 and 183 cM who have been tagged as thirds), it appears to me that you must pass 200 to be called a second. Too strict in my opinion.

                  My paper third (73) is called a 4th. Again no relation to ISOGG numbers and overly conservative.

                  ~~~~
                  The bottom line for AncestryDNA is now 6.0. Prior to May, it was 5.0, so I suppose most of the 5 to 6 cM matches were purged.

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                  • #10
                    I don't know what number Ancestry is using now for calling the end of matching, but I'm really wishing that they raise it.

                    Currently at Ancestry I'm being inundated with 5th to 8th cousin matches who have no trees and therefore no way to compare a match to see if they might be related to someone I can identify. Most of the 5th to 8th cousins don't connect in what Ancestry calls "Shared Matches", and most of the recent matches have no trees.

                    I've been spending a few minutes each day looking through new matches and finding nothing. Therefore, I end up tossing the matches into the trash can. I use the trash can as the only way to file useless matches. If there is something or anything on a matches page that might be of any use, I use the gold star. Otherwise the few matches I have a hope of connecting with can't be distinguished in any way on a quick look through.

                    I'm figuring that in a couple of weeks I'll probably be over the 20,000 match mark. Ancestry has a great marketing program for those people searching for the "ethnicity", whatever that means, but the results are that you have a "gazillion" matches that don't know diddly squat about their families, and they expect to be handed a family tree, by putting in a couple of names. Hah!

                    Sorry for the rant.
                    Last edited by keigh; 24 July 2016, 06:54 PM.

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                    • #11
                      Keigh: Abrams stated above that Ancestry's cut-off is 6 cMs. Shared Matches cut-off is 4th Cousins.

                      I have just finished going back through my Removed Matches file of 13,700 people and have found ~100 new shaky leaf matches. They must have been mistakenly dumped there when they made the changes last year, or the match, or I, added people to our tree which triggered a match in the Removed File.

                      You have almost 20,000 matches at Ancestry? Or did I read that wrong? If so, that must be a record.
                      Last edited by Biblioteque; 25 July 2016, 08:35 AM.

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                      • #12
                        Originally posted by marietta View Post
                        Keigh: Abrams stated above that Ancestry's cut-off is 6 cMs. Shared Matches cut-off is 4th Cousins.

                        I have just finished going back through my Removed Matches file of 13,700 people and have found ~100 new shaky leaf matches. They must have been mistakenly dumped there when they made the changes last year, or the match, or I, added people to our tree which triggered a match in the Removed File.

                        You have almost 20,000 matches at Ancestry? Or did I read that wrong? If so, that must be a record.
                        I'm currently running just over 18,000 matches and usually getting about 250 or more every 7 days. I haven't even gotten through my last weeks matches, 244 when they dumped 277 more on me this week. And I'm spending just a few seconds in some cases checking whether the match that says it has "No Tree" actually has a tree or even shared matches. A number of my 5th to 8th cousins do have shared matches with my 4th to 6th cousins. Unfortunately, many of those shared matches have no trees and/or share matches to others who have no trees.

                        It seems more and more people test and they have no tree, or just 3 or 4 names and of those half are private!

                        And I think if I have one more person write and say that he or she was adopted, I think I'll scream!! They'll have developed a tree for only the father's side or the mother's with the other half of their tree blank or private. But there is a 50% chance that any match they have will connected to blank or private. I wonder at times if they even think about that?

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                        • #13
                          Interesting

                          Yeah I'm awaiting my Ancestry (Canadian site) results. Love to try out Family Tree DNA as well. Never heard of you guys before.

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                          • #14
                            I'm a little confused by their tree. The close match is a female. She has not been linked to a tree. The test was administered by someone else and it shows two trees when I click view match. The administer is a male and when I click trees there are two. I can't remember but let's say the match is A.B. In the two trees the first tree is the first generation is male and a the example says A.B. In the second tree the first generation is then also listed A.B but is female.
                            Many of the matches are like this. Can someone explain this to me please? The administers name is in his user name and that last name is in one tree a lot under the males. Someone said that a son most likely tested his parents. My children bio father is 1/2 Italian and the match is also part Italian. My children and their shared matches are also Italian. None of the names in either tree is Italian. It could still be another match. I've been messing around with my sons tree and put some
                            of the people to his tree to awe if I could get some shared matches but nada. The person has not logged in or responded to my message. Hoping they do at some point as this is his closest match finally. He doesn't have many matches at all.

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