14 September 2015

Genetic Genealogy

Genealogy can be an exciting hobby. There is the excitement of hunting for a missing piece of information; the satisfaction of figuring out a puzzle that others couldn’t solve; and the joy of adding a new person to the family tree.

In recent years there has been a new tool to help locate relatives and verify the connections on your family tree. That tool is DNA testing for genealogical purposes. The three main companies that do DNA testing are 23andMe, Family Tree DNA, and AncestryDNA.

Segments of DNA are measured by centimorgans (cMs). Usually the more cMs that 2 people share the closer the relationship is. The chart below illustrates how the amount of DNA we inherit from our ancestors can vary widely, even by the time you reach the Second Cousin level of relationship.

If you look closely at the following chart you will see that second cousins John and Allison share 330 cMs of DNA, while John only shares 31.3 cMs with Albert another one of his second cousins. That is quite a difference, yet both relationships are that of second cousins. Yet, the amount of DNA that Jeanetta shares with those same two second cousins is much closer. She shares 120 cMs with Allison and 124.5 cMs with Albert.

This is because of how dna is recombined and passed down through the generations. I plan on doing a more detailed description about that in a future post, for now I just wanted to share this part of it.

1. Frederick J. Newman and Louise Grace Boyer are the common ancestors for: Linda, Mark, Albert, John and Jeanetta.
2. Walter Lucier and Ellen Bownes are the common ancestors for: John, Jeanetta, David and Thomas.
3. Thomas Riordan and Grace Janvrin are the common ancestors for: John, Jeanetta, Heather and Allison.