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42.
Revisiting Speed and Balding - Blog comment by lkessler - 8 Nov 2017
... in the model is extreme endogamy for 50 full generations without any external DNA being added to the pot. We all know what happens in endogamy. Segments passed down multiple ways on multiple lines. This could very well be the reason for the expanded G values in their simulation. No external DNA added for 50 generations. If their ...
43.
Revisiting Speed and Balding - Blog comment by debbiek - 8 Nov 2017
Louis
It makes no difference whether one is studying diseases or detecting DNA relatives. It's still necessary to identify related people in the database.
The reason the testing companies filter small segments under 6 cMs or 7 cMs is not to exclude small segments from distant generations but for the very practical reason that these small segments cannot be ...
44.
Revisiting Speed and Balding - Blog comment by lkessler - 8 Nov 2017
... mention is anything about filtering for only people who would show up in a person's DNA match list. And that makes sense because you are studying diseases, not DNA relatives.
DNA testing companies filter the matches to only include people with a minimal total cM match and a minimum largest cM match. ...
45.
Revisiting Speed and Balding - Blog comment by lkessler - 8 Nov 2017
... your talks and meeting you in person in Houston this weekend at the FamilyTree DNA's Genetic Genealogy Conference.
Louis
46.
Revisiting Speed and Balding - Blog comment by dougspeed - 7 Nov 2017
... I could keep track of exactly what happened in each mating, i.e., which pieces of DNA a child got from their dad's maternal DNA, and which from their dad's paternal DNA, etc. I ended up with a long list of identity by descent (IBD) segments of varying length, allowing me to ask the question, if I ...
47.
Revisiting Speed and Balding - Blog comment by jimbartlett - 6 Nov 2017
... and then fall - keeping the total under the curve at 100%. Two weeks ago, AncestryDNA had me at 50,000 Matches (probably over half are false), and 2,000 4C Matches (some probably 5C or 6C) - that would result in a flatter curve than my percents above..
Thanks again for your expertise and level headed reasoning about this topic. Jim
48.
Triangulation does NOT mean IBD - Blog comment by lkessler - 4 Oct 2017
Debbie: Well, I'm just looking at the results. And FamilyTreeDNA seems to have many fewer disprovals of IBD by parents at any given cM level than AncestryDNA does.
49.
Triangulation does NOT mean IBD - Blog comment by debbiek - 4 Oct 2017
No I think it means the opposite. FTDNA can't use a higher threshold because they are not using phasing or any algorithms to remove pile-ups. The vast majority of matches that don't match either parent at AncestryDNA share under 9 cMs. Ancestry's own tests published in their white paper ...
50.
Triangulation does NOT mean IBD - Blog comment by lkessler - 3 Oct 2017
Very interesting, Debbie. So then it seems that FTDNA's criteria of at least one 9 cM segment is better (i.e. produces fewer false matches) than AncestryDNA's combination of phasing and inclusion of segments down to 6 cM. That may be indicative that AncestryDNA's ...
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Revisiting Speed and Balding - Blog comment by lkessler - 9 Nov 2017