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.