Molecular Genealogy

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Genealogy doesn't often make news headlines, but in recent months it has been a hot topic in newspapers worldwide. The reason?  Genetics and genealogy have merged into an amazing new research field which allows us to prove family connections beyond all doubt. Nature Magazine recently reported that DNA testing was used to support the probability that Thomas Jefferson fathered the last child of Sally Hemmings. DNA testing in 1997 established that Cheddar Man, Britain's oldest complete skeleton buried over 9000 years ago, has descendants still living in Cheddar. Traditional genealogy research and DNA have even come together to identify the remains of missing American servicemen. Now new research studies claim that we can use DNA not only to prove a relationship to an individual, but to actually determine our ancestry.

Dr. Scott Woodward and his research group at Brigham Young University in Provo, Utah are among the pioneers in this new research field. The Molecular Genealogy Research Group, under his direction, is using the genetic information contained in DNA to reconstruct worldwide family trees. This study is based on the fact that each individual carries within them a unique record of who they are and how they are related to all other people on earth, both living and dead. "We are a walking, living, breathing record of our ancestors," says Woodward. "Genealogy is really a genetic question."

We all know that DNA has the ability to identify individuals but, because it is inherited, there are also regions of the DNA strand which can relate an individual to his or her family (immediate and extended), tribal group and even an entire population. Molecular Genealogy can use this unique identification provided by the genetic markers to link people together into family trees. Pedigrees based on such genetic markers can mean a breakthrough for family trees where information is incomplete or missing due to adoption, illegitimacy or lack of records. There are many communities and populations which have lost precious records due to tragic events such as the fire in the Irish courts during Civil War in 1921 or American slaves for whom many records were never kept in the first place.

The main objective of the Molecular Genealogy Research Group is to build a database containing over 100,000 DNA samples from individuals all over the world. These individuals will have provided a pedigree chart of at least four generations and a small blood sample. Once the database has enough samples to represent the world genetic make-up, it will eventually help in solving many issues regarding genealogies that could not be done by relying only on traditional written records. Theoretically, any individual will someday be able to trace his or her family origins through this database.

In the meantime, as the database is being created, molecular genealogy can already verify possible or suspected relationships between individuals. "For example, if two men sharing the same last name believe that they are related (i.e. they have a common ancestor from whom they got the last name), but no written record proves this relationship, we can verify this possibility by collecting a sample of DNA from both and looking for common markers (in this case we can look primarily at the Y chromosome)," explains Ugo A. Perego, a member of the BYU Molecular Genealogy research team.

The two basic principles that makes Molecular Genealogy possible are:

1. We inherit our DNA from our parents. DNA is shuffled, recombined and transmitted from one generation to another. Each individual on this earth received 23 pairs of chromosomes from their parents (23 from dad and 23 from mom). Because DNA is maintained to a certain degree from one generation to the next one, it is possible to trace family lines by identifying specific markers.
   
   
2. The inhabitants of the Earth are more closely related than what it is generally thought. Today there are 6 billion people living on this planet. If we do some math, and we consider a generation to be about 25 years, 30 generations ago (=750 years) every individual living today would have over 1 billion unique ancestors. The estimated world population for the year 1250 AD was 400 million people. This means that the number of actual ancestors for each individual is smaller than the number of possible ancestors and that we all start sharing common ancestors within just few generations. These common ancestors were able to transmit specific markers that are present in our DNA and that we share with others today.
   

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