Saturday, March 14, 2009

My Y-DNA Results - Post 4: GeneBase Possible Matches

My daughters gifted me a 20-marker Y-DNA test from The DNA Ancestry Project ( for Christmas. I sent it in via mail in mid-January and had not heard anything back from them. I checked into it on Monday and found that my results were available on Genebase.

The first post described Getting Started on the web site. The second post described Reading the Markers - seeing my 20 Y-DNA markers for the first time. In Post 3: GeneBase Family Tree I uploaded my family tree to Genebase and showed the results.

In this post, I will show the possible matches in the Genebase Y-DNA database.

Here is the welcome screen in Genebase. I had to search hard for the link to the possible matches results.

The link to the possible matches is under the "DNA Ancestry" tab and then, for the Y-DNA results, under the "Paternal Line" link, and then click on the "DNA Reunion" link. The resulting screen looks like this:

On this screen, it says:

Compare your Y-DNA STR markers to other participants in the database. This search compares every marker that you and other participants have tested.
Show participants who have tested at least [6] of the markers that I have tested.

Allow a maximum genetic distance of [4]

I decided to set the marker number to [10] and the maximum genetic distance to [2]. I clicked on the great big "Find Matches" button (no mystery here!):

Finally. I have 114 Genetic Matches that satisfy my match criteria of at least 10 markers and a genetic distance (GD) of 2. There are 7 that match 10 out of 10 (GD+0) - but none of them are anything close to a Seaver surname. There is one match that is 19 out of 20 (GD+1), three that are 12 out of 13 (GD=1), one that is 11 out of 12 (GD=1), and one that is 19 out of 20 (GD=2).

I can compare my genetic markers with those of another tester by clicking on the "Compare Y-DNA" icon in the right-hand column - I chose the 19 out of 20 (GD=1) person - and saw:

The only marker that was on my test that we don't match on is DYS390. He tested 44 markers, more than I did. I can click on the "Family Tree" icon in the right-hand column to see his the family tree that he uploaded to see if there are any surnames or place names similar to those on my family tree. There are no common surnames, and place names are not given.

I could click on the "Contact this user" icon in the right-hand column to send a message to this person.

There is also an icon for Time of Most Recent Common Ancestor (TMRCA), so I clicked that. It said:

Base upon a mutation rate of 0.002 for Y-DNA STR markers, you and XXXX XXXX XXXXXXXX most likely shared a common paternal ancestor 13 generations ago.

Cumulative probability ranges are as follows:

The probability that you and XXXX XXXX XXXXXXXX shared a common ancestor within the last 22 generations is 50%.

The probability that you and XXXX XXXX XXXXXXXX shared a common ancestor within the last 39 generations is 80%.

The probability that you and XXXX XXXX XXXXXXXX shared a common ancestor within the last 62 generations is 95%.

That certainly puts it all in perspective, doesn't it? The first line is very misleading! I don't associate the words "most likely" with anything less than 80% certainty. Certainly not 13 generations! The correct word in the first sentence should be "might have" rather than "most likely."

The site provides a table for likelihood and cumulative probability of TMRCA out to 150 generations. The cumulative probability of TMRCA for 13 generations is 26%.

This part of the web site and database is very well thought out. It takes some poking around to find the icons in the right-hand column - a guide at the top of the table would be very helpful.

I will continue looking for possible Y-DNA matches in other database in the next post.

1 comment:

Anonymous said...

Randy it can get very hairy reading those data bases. Recently they are learning some are not as accurate as thought and are redoing them. In time I suspect they will be far more accurate than now. Now we will see if this things accepts my comments so far it has not.

Have great day...Susi