Saturday, February 1, 2014

X Factor: Another Adams Cousin, part 2

Four simple rules of X-chromosome DNA inheritance:
  1. 1.      Girls inherit it from their mothers.
  2. 2.      Girls inherit it from their fathers.
  3. 3.      Boys inherit it from their mothers.
  4. 4.      Boys DO NOT inherit it from their fathers.
Of these four rules the last is the most important. Anywhere on your pedigree chart where there is a father to son relationship, NO X-DNA flows. Y-DNA flows instead. As frustrating as this last rule can be sometimes, it can also be part of the solutions for some of our genealogical mysteries. But like most clues, they only help us when we are paying attention.

In December I blogged about a newly discovered 39th Adams first cousin. At the time I was operating with blinders on. Those blinders were a couple of vague recollections some of the local old timers had that an Adams boy may have had an illegitimate child that could have been my new cousin Jim. In my earlier post I had called him Joe to maintain some semblance of privacy. However, now with his blessing, I am "blowing his cover."

In my book, Crash Course in Genealogy, Rule #4 for genealogists is "Believe everything and believe nothing you hear or see in print." In my first efforts to unravel the mystery of Jim's birth, I was following the "believe everything" part of this rule but ignoring the "believe nothing" part. DNA does not lie. However, sometimes our ability to read the information it contains is considerably less than 20/20. As a result I started down a wrong path of investigating my four Adams uncles as the candidates to have been Jim's father. This effort now is revealed to have been a waste of time, money and other resources.

This week I decided to mount a second investigation. Now that I assumed that we had the investigation of his father under control and that a couple more autosomal DNA tests of strategically chosen cousins would reveal his biological father, I would start to stir the pot about his biological mother. Boy did I have that one backward.

I went to where both Jim's results from and mine from various sources were parked for analysis. I decided to search Jim's X-DNA against the database to see if he matched anyone who might be related to his biological mother. Of course I came up because we were 1st cousins. So I concentrated on the others who matched Jim. Only later did I realize that I was ignoring the most important of Jim's matches. His match with me. In the chart below, the blue portions of the bar graph represent the areas where we had matching segments greater than 3 cMs long:

If Jim and I share these kind of matches on our X chromosomes our mothers were closely related. Jim's mother must be a sister of my mom. That realization turned our investigation around 180 degrees. Instead of investigating my four uncles to determine which was Jim's father, we needed to investigate my nine aunts to determine which was his mother. What a paradigm shift!

With that realization, another bit of recently acquired information took on new meaning. Jim has recently initiated an effort to find out what information court records may contain. He writes: 
The circuit court clerk was surprised that I was tagged with the family name of the father rather than the mother.  Apparently it was more common around here at that time for an unwed mother to pass her family name, not the father's, on to the child.
 When I was three years old, in the circuit court I was adopted by Morgan and Florence Jones and my name changed from James Edward Adams to James Edward Jones. The circuit court clerk will be looking at that adoption record and the birth certificate if available. It feels unlikely that there was any earlier name change.

Now based on our X-DNA we know why the file was tagged the way it was in circuit court. His mother was an Adams. So now we have a different task. Jim's mother could not be my mother. We share enough DNA to be 1st cousins. We would need to share about twice as much to be half-siblings. One of my aunts can be eliminated because she gave birth to a daughter the month before Jim was born. Another is highly unlikely because she gave birth the month Jim was conceived. Of the remaining seven, four were still living at home during the 1930 census which was recorded about a year and a half before he was conceived. These four may get our first attention. BUT if we have learned anything, it is not to overlook any possibility until it has been completely eliminated.


  1. Dr Dave
    This is a well explained teaching example of rule 4 and the folly of records

  2. Yes Jean, some of our best learning experiences are created by our mistakes.

  3. Dr. Dave,
    I thoroughly enjoyed reading about you in the Tennessean. I am a member of the Lebanon (TN) Breakfast Rotary Club and was curious if you would agreeable to giving a short 20 talk at a scary time of the morning (we meet from 6:30-7:30am on Thursday March 20, 2014). My email address is Thanks! Greg B.