PARKER Surname DNA Project
Why only males can participate in this surname project

If you are new to DNA testing for genealogy, you probably wonder why only males can be tested for this project. The chart and explanation below show how the sex of a child is determined by the presence or absence of a Y chromosome. We are fortunate that the sex chromosomes are different from the other 22 pairs of chromosomes. The Y and X chromosomes are so different that they do not exchange genetic material (DNA). The Y chromosome is passed from father to son only and contains no DNA from the mother. These properties allow us to use the Y chromosome to track the male line only, making it a very powerful tool for genealogy.

    The chart below shows two lines that descend from a common ancestor, James PARKER.  Each son, John 1767 and Thomas 1769, received a copy of the Y-chromosome of their father James. If we could test brothers John and Thomas, we would expect them to match exactly on their Y-DNA. The same condition holds for each succeeding generation. However, the only living males to test are 4th cousins Elijah, born 1915, and Robert, born 1924. Each of these men are 5 generations from their common ancestor James. The names have been changed, but we have actual data for a genealogy like this in which Elijah 1915, and Robert 1924, have an exact match on their Y-DNA. The matching Y-DNA of Elijah and Robert tells us that they both descend from the same ancestor. Traditional genealogy research identified that ancestor as James PARKER, born 1734 in Pennsylvania.