Announcement

Collapse
No announcement yet.

Can I reverse this DNA statistics chart?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Can I reverse this DNA statistics chart?

    About halfway down this page http://www.isogg.org/wiki/Autosomal_DNA_statistics is a color chart showing DNA inheritance. If I'm reading it correctly, I should have about 6.5% of my great-great grandfather's DNA. Can I reverse this chart to guess how much DNA from a certain group was present in a previous generation?

    For example, and this is just hypothetical: If FTDNA told me 6.5% of my DNA was from a certain group, is this chart telling me that about 50% of my great-great grandparents's generation's DNA would identify as belonging to that ethnic group?

    Thanks for any insight.

  • #2
    myOrigins is looking at patterns from thousands or many hundreds years ago (more than 500), so the short answer is no.

    If I understood your question

    Mr. W

    Comment


    • #3
      The results are from Population Finder(geographical origin) run through Gedmatch(ethnic origin).

      The real world situation is that I have PF results from two branches of the family from testers born in the early 1900s. One has an ~8% +/-2% match to an ethnic group. The other is assumed(I haven't run them through Gedmatch.) to have a ~6.5% +/-2% match to the same group. The branches moved out of their original area to separate states around 1800 with no known contact after that and don't appear to have intermarried with the ethnic group since then.

      The branches don't connect on paper, just through DNA, but a new paper-trail breakthrough all but places them in the same county around 1800. If the dilution of DNA from the ethnic group follows that chart but in reverse, it would line up with the new paper trail. My thinking is that if the ethnic group is still showing up in the 6.5-10% range for the testers and the dilution rate matches the chart, wouldn't the ethnicity have to be about 50% in the great-great grandparent generation? If that generation wasn't 50%, wouldn't it be diluted out of the PF results by the testers' generation?

      If my family was 50% ethnicish in the late 1700s, it would give me a concrete direction for researching how to link the branches up and get through the brick wall in my branch that I've had forever. But I've had a lot of rabbit trails and false leads. Before I jumped on this speculation, I wanted to run it past the forum and see if my thinking was on target about the dilution of the ethnic group's DNA.

      Comment


      • #4
        In that sense, yes. But you should observe that people in the forum report populations they were entirely not aware of :-)

        Also please take a look at the section Distribution of genealogical relationships for given amounts of shared DNA in http://www.isogg.org/wiki/Autosomal_DNA_statistics. Sometimes a noticeable deviation from the average expected percentage is observed...

        [I think the above sentence cries for better English ]

        Mr. W

        Comment


        • #5
          Originally posted by dna View Post
          In that sense, yes. But you should observe that people in the forum report populations they were entirely not aware of :-)

          Also please take a look at the section Distribution of genealogical relationships for given amounts of shared DNA in http://www.isogg.org/wiki/Autosomal_DNA_statistics. Sometimes a noticeable deviation from the average expected percentage is observed...

          [I think the above sentence cries for better English ]

          Mr. W
          Thanks for the answers.

          The ethnic group wasn't an ancestral population I was aware of, but it's one I'm happy to be associated with. Part of the adventure now is finding out how it became assimilated into my family.

          Something that's been noticed by a better researcher than me is a pattern of intermarriages between a cluster of what should turn out to be previously unknown ancestors of my direct line and its "allied" families. I don't know if the marriages are close enough to affect the percentages, but I'm braced for impact.

          Does anyone else have any thoughts? I see a lot of thread views. I need all the ideas I can get.

          Comment


          • #6
            Originally posted by Sparky View Post
            [----] Does anyone else have any thoughts? I see a lot of thread views. I need all the ideas I can get.
            Consider tracing mtDNA lines...

            Comment


            • #7
              Do you know how hard it is to find girls before 1850? he asked rhetorically. According to census records, there were very few of them!

              But I'll certainly put more effort into that.

              Comment

              Working...
              X