Genetic Triangle

We have a promising genetic cousin match at 23andMe.  We'll call him J.D.  He matches both my father and my father's third cousin, which quite a few people do.  The difference is that the match, or the identical segment of DNA, is the same among J.D., my father, and our third cousin!  Perhaps triangulation describes this scenario?

Here is what the graph looks like:

The common ancestors shared by my father and his third cousin are their great great grandparents, Calvin Cook and Mary Neil.  They were born around 1830 and lived in Morris and Hudson Counties in New Jersey.  We do not know at this point if the shared DNA on chromosome 13 is from Cook or Neil.  We need to go back in time in both trees and we should find an ancestor in common with J.D.  We do not know how many generations back we must explore until we find a common ancestor.  All we know right now is that the match is through Calvin Cook's line or Mary Neil's line, which greatly narrows our search.

This illustrates why you need document-based genealogical research to help you with DNA genealogy.

Compare the above graph to this graph.  A. D. matches both my father and his third cousin, but on different chromosomes.  We cannot determine with this information if the double matching indicates a single common ancestor.

New Genealogy Features at 23andMe

23andMe has launched some new features to assist in figuring out how it is that your matches match you.  You can type in your family tree.  This is a Beta version and is not cooperating with me for dates and locations.  I do not know if this will be a handy reference for your matches or if the site will somehow propose possible connections based on the comparisons of the trees.

You have always been able to list surnames in your profile.  Many a match has written to me that we can't be related because they don't recognize any surnames in my profile, and then cut off contact.  This is rather silly, especially when the person has only researched one or two generations of their own tree.  If everyone knew every ancestral surname on every line for the past 500 years, then genealogical research and DNA studies would not need to exist.

The next feature is a map with locations of your genetic cousins marked in purple.

23andMe
Map of matches of my father

23andMe
Map of matches of my mother

Compare the maps of my father versus my mother.  My mother has more matches, which we knew, but with a clear concentration in Eastern Europe that my father does not have.  The numbers represent how many people claim such a location, so the hidden numbers could be 1 or 20.  You have to zoom in to see.

23andMe
Locations in the United States of my mother's closest matches

Manipulation of the degree of cousinship brought me to the New York area, the only location of my mother's closest cousins in the United States.  You can click on the little purple flag to reveal the relation and surprise!  All of these locations are for the same cousin.  The locations are any places mentioned in the profile, instead of a birthplace, which would have been more useful.

So onward to the next new feature:  shared surnames among the matches.

23andMe
Shared surnames among genetic matches for my mother

I was not surprised to see Cohen as the most frequent surname among my mother's matches.  As with the place maps, the common surnames are not the name of the match, but rather any surname mentioned in the profile.  I am not sure what the enrichment value means.  I figure it is some measure of the degree of commonality of a surname in general.

23andMe
Shared surnames among genetic matches of my maternal uncle

My mother's brother's matches revealed the Irish surnames.  The problem that I am having with these Irish names is that they are so common anyway.  Most of the Irish matches have at least one ancestral surname in common with us.

I turned to my father's common surname list next, putting my extensive research to the test.

23andMe
Shared surnames among genetic matches of my father

I have Marsh and Strong in my paternal ancestral lines.  I have been seeing a lot of Adam.  Hall and Hickman are interesting because I am working on a possible Hale and Hickman connection from the Strong line.

These new genealogy tools will be useful and are a welcome addition at 23andMe.

Close Genetic Cousins

Finding close cousins through shared DNA at 23andMe is exciting but draining at the same time as we attempt fruitlessly to figure out the connections.

Take a look at the shared DNA between my father and his third cousin, who was known before the DNA studies.  (Third cousins share a pair of great great grandparents.)

23andMe.com

My mother has several matches (excluding her brother and me) who share more genetic material than this.  Most do not respond to requests to exchange information, which is very disappointing.  The select few who have shared information with me can now be compared to one another.  The idea is that genetic cousins can be clustered together based on matching one another, forming a working family tree.  When I compared my mother's closest relations to one another, I was surprised to see quite a few of them matched each other even more closely.  The problem is that nobody knows how anybody else is related.  In theory, if we trace back to great great grandparents, we would be looking at identical trees in one branch.  This has not happened yet.

Indexing Project: New York City Death Ledgers

The Italian Genealogical Group is doing great work again by indexing the Death Ledgers of New York City.  Deaths were recorded in a list format in ledger books until about the year 1866, when death certificates were issued.  The entries in the index will not be linked to an image.  You can order a copy of the ledger page from the New York City Municipal Archives.  This will be a great finding aid, but remember to use any online index to locate the original record.

Page of ledger of deaths, New York City, 1824.
Note that several people were "unknown."
Also note the young ages, relative to today's longevity; death from Small Pox; and burial in Potter's Field.



An index is on the way!

Prolific and Redundant

In researching the query posed in a previous blog post, "Royal Genealogy," what are the chances that people of today are descended from Charlemagne?  Quite good, it seems.

"Ancestry and Mathematics" is a very interesting article by Bruce Railsback and on point for the Charlemagne discussion.  Every time you travel back in your family tree, your ancestors double.  You have two parents, four great grandparents, eight great great grandparents, and so on.  Go back ten generations and you have 1,024 ancestors.  Go back twenty generations and you have over one million ancestors.  Go back thirty generations and you have over one billion ancestors.  The problem (aside from not being able to document so many people so far back in time) is that there were not that many people alive on the planet way back when.  The population of the planet did not reach one billion until around the year 1800 A.D.

So how can you have more ancestors than the population of the planet?  Many of your ancestors from different lines were the same people.  You are your own cousin.

What does this have to do with Charlemagne?  He lived about 1200 years ago.  If you use a conservative four generations per century, that's about 48 generations ago, when you should have billions of ancestors.  There were only about 300 million people on the planet at this time, though, which includes children and people who did not leave any descendants.  Charlemagne was one of those 300 million and he did leave descendants, so it is entirely possible that you are descended from Charlemagne.

Could this be why I have so many "genetic cousins" with no apparent connections when comparing family trees for a few hundred years?  If not Charlemagne, maybe another prolific ancestor?  I will keep this theme in mind for a future blog post.