One Segment at a Time

A Segment-ology TIDBIT

The old saying: How do you eat an elephant? One bite at a time. We can, and should, apply this advice to Triangulated Groups and Chromosome Mapping. Take it a TG/segment at a time.

These days, the Matches are pouring in, and it’s easy to get overloaded with data. So I’m setting two goals:

  1. Form one new TG every day
  2. Communicate with the Matches in a TG each day

Each person’s objectives and available time are different, so set the timeframe to suit your own situation (every other day, each week or whatever). The point is to put a goal and plan in place.

There are about 400 TGs spread over my 45 chromosomes. So at one-a-day, it would be March 2018 before I could form every TG for my Dad (I’m just getting started on his chromosome map).  But by then this long ignored project would be done; and his map would provide extremely valuable information for my chromosome map.

And if I send out a small group email (average 10 Matches) to the most significant Matches in a TG every day, it will be March 2018 before I focus on every TG. But two good things will happen: 1) I will have focused on every TG, and worked on the Common Ancestor; and 2) For about every 10-20 emails/messages I send out, I determine a new Common Ancestor. So by March 2018 I’ll have another 200 or so Common Ancestors. [NB: Each CA is not necessarily the correct genetic link for the TG, but they are all genealogy cousins and provide important clues in our quest to “walk the ancestor back” and/or obtain multiple agreements on the TG CA.]

In other words, we reap what we sow – we get a percentage return on the communications we send to Matches – the more we send, the more we get in return.

Again, everyone’s situation is different. All I’m suggesting is to set a goal, and schedule some time for TGs and chromosome mapping. Take a periodic bite out of the atDNA elephant!

 

[22H] Segment-ology: One Segment at a Time TIDBIT by Jim Bartlett 20170218

Uploading to GEDmatch

A Segment-ology TIDBIT

There are 3 basic steps:

  1. Go to www.GEDmatch.com and create an account. Your account is based on your email (so carefully choose the email you’ll want to use), and a password (known only to you – if you forget it, you’ll need to reset the password). You’ll get your own homepage at GEDmatch, which will list any DNA kits you upload and/or any GEDcom.
  2. Go to your DNA company and download your raw DNA data file – note the name of the file and where it is saved (usually your Download folder); leave the file zipped (do not unzip it)
    • AncestryDNA – At “Your DNA Results Summary” page, click on top-right: “Settings” (gear icon); click on “Download Raw DNA Data” TAB and follow their directions, which will involve an email and entering your password again.
    • FamilyTreeDNA – on your main “Dashboard” page, under the Family Finder section is a link: “Download Raw Data” – click on that; and then click on the download arrow for “Build 36 Raw Data Concatenated”.
    • 23andMe – UPDATED (1/20/17) at GEDmatch just click on “23andMe fast and easy” – the process takes about a minute!
  3. Log into GEDmatch and upload your raw DNA data file – in top right box, click on “Generic Upload”; then fill in the form; in the last row: Click on “Browse” means: Click on “Choose File” button. Do that and navigate in your PC folders to where your raw DNA data file is, and click on it. Then Click on “Upload”. Wait several minutes for the process to complete and give you a statement that it is finished.

Note: you can, and should, also upload a GEDcom file (your family Tree) – on your main GEDmatch homepage, see the link for “Genealogy – Family Trees”.

I hope to see you on GEDmatch!

 

[22G] Segment-ology: Uploading to GEDmatch TIDBIT by Jim Bartlett 20170119

Walking the Ancestor Back

A segment-ology TIDBIT

Here is an example of walking the ancestor back. I just extended one more generation today, giving four intermediate cousins all in the same line of descent from the CA.

The TG is [14B24] 18-30Mbp about 18cM – [14B24] indicates Chr 14, start in 10-20Mbp area, ahnentafel to CA starts 2-4 – some show this as PP]

The following line of descent is all in VA/WV [the four CAs are bolded]:

Common Ancestor: Sylvester WELCH 1696-1753; 1m 1720 Anne SPENCE: Match KBD at ADNA for 9.9cM is 6C1R

MRCA is son: Sylvester WELCH 1729-1810; m c1752 Jemima CARROLL; Match PDJ at FTDNA for 10.1cM is 5C

Dau: Elizabeth WELCH 1777-1847; m 1797 James FLEMING

MRCA is dau: Sarah FLEMING 1809-1854; m 1827 John H BARTLETT: Match LWA at FTDNA for 16.2cM is 3C

MRCA is son: James V BARTLETT 1836-1920; 1m Elizabeth J NEWLON: Match CK at 23andMe for 54.1cM is 2C1R [this segment overlaps the next TG, too]

Son: Ira S BARTLETT m Blanche O MITCHELL

Son: James V BARTLETT m Betty V BAKER

Son: jvb jr = me!

 

A Segment-ology TIDBIT

[22F] Segment-ology: Walking the Ancestor Back TIDBIT by Jim Bartlett 20170103

Save the Clues!

A Segment-ology TIDBIT

In genealogy if we look for Thomas BARTLETT in the census and find three entries with that name, we don’t discard them all if we cannot immediately figure it out. We record them all and look for more evidence. The same concept applies to DNA. Record all the Common Ancestors you find with a Match. Even if the Match is a 2nd cousin (2C), she may also be a 5C or 8C on a different line. One of her shared segments may go back to that more distant ancestor – it’s happened to me! Don’t disregard a “pile up” of shared segments which Triangulate (just because they may be from a very distant ancestor). Science tells us that some of those 7-20cM shared segments will be with closer cousins – it’s happened to me, often. Don’t disregard a distant cousinship beyond 5C with a Common Ancestor. Save the clues. As new Matches come in, you may find supporting evidence for that CA in the TG – it’s happened to me. I have 11 out of 35 Matches, on one TG with the same 7G grandparents (some of them are 6C and 7C, the rest are 8C).

 

[22E] Segment-ology: Save the Clues TIDBIT by Jim Bartlett 20170103

Only One Comparison Needed to Add a Segment to a TG

A Segment-ology TIDBIT

Start with a list of your overlapping shared segments – they all match you (two triangle legs). Find two of these shared segments that match each other (third triangle leg) to form a Triangulated Group! All the rest of the shared segments in your overlapping segment list need only match one of the shared segments in the TG – any one of them with a good overlap – to be added to the TG. The explanation will take a long blog post with diagrams – but the thrust is that forming a TG basically identifies that segment just as good as trio-phasing. So trust me! If a shared segment doesn’t match the TG, it will match the other, overlapping TG; or it is IBC (it happens for some shared segments under 15cM). As a Quality Control measure, I often make a second comparison – it always matches!

 

[22D] Segment-ology: Only One Comparison Needed to Add a Segment to a TG TIDBIT by Jim Bartlett 20170101

Roughly Right is OK for Genealogy

A Segment-ology TIDBIT

A Chromosome Map divides each chromosome into segments [or TGs] from specific ancestral lines. The data we get is fuzzy (see Fuzzy Segments), so the size and boundaries of these ancestral segments is a little fuzzy. But so what! For genealogy purposes these ancestral segments are large “targets”. Most shared segments with Matches easily hit these targets. The ancestral line “owns” their target segment. For genetic genealogy, that’s what matters – linking Matches and Common Ancestors with segments. It doesn’t make any difference if the shape or size of the target segment (TG) is a little blurry.

 

[22C] Segment-ology: Roughly Right is OK for Genealogy TIDBIT by Jim Bartlett 20170102

Number of Matches on a Segment (or TG)

A Segment-ology TIDBIT

Segments from Ancestors with large families will generally have more Matches (in general, the larger the families, the more cousins you have). Segments from more distant Ancestors will generally have more Matches (in general, the more distant the ancestor, the more cousins you have). Segments from Ancestors in Colonial America will generally have more Matches (in general, more Americans have taken the DNA tests). Segments from endogamous Ancestors will have more Matches (because of endogamy, there is more matching DNA).

 

22B Segment-ology: Number of Matches on a Segment (or TG) TIDBIT by Jim Bartlett 20170101