Your direct paternal lineage is the line that follows your father’s paternal ancestry. This line consists entirely of men.
Your Y-chromosome DNA (Y-DNA) can trace your father, his father, his father’s father, and so forth. It offers a clear path from you to a known, or likely, direct paternal ancestor.
DNA Matching for Family History
Your Y-DNA may help you find genetic cousins along your direct paternal line. Planned comparisons are the best choice. To set up a planned comparison, select two men who you believe share a direct paternal ancestor. Have both men take a Y-DNA test. If they match exactly or closely, then the DNA evidence supports the relationship. If they do not match, the result is evidence refuting the relationship. When you discover a match outside of a planned comparison, you can still find your common ancestor with matches. To do so, use your known paternal genealogy. For each match, look first for a shared surname if you come from a culture where surnames have followed paternal lines. Then look for common geographic locations on the direct paternal line. Work through each of your ancestors on this line as well as their sons, their sons’ sons, and so forth. Comparing genealogy records is vital when using Y-DNA matching to help you in your research. You need to enter all that you know about your direct paternal line in your myFTDNA account.
The Science of Your Direct Paternal Line
Your Y chromosome is a sex chromosome. Sex chromosomes carry the genetic code that makes each of us male or female. All people inherit two sex chromosomes. One comes from their mother and the other from their father. You and other men receive a Y chromosome from your father and an X chromosome from your mother. Men and only men inherit their father’s Y chromosome. Thus, it follows the same path of inheritance as your direct paternal line. Paternal line DNA testing uses STR markers. STR markers are places where your genetic code has a variable number of repeated parts. STR marker values change slowly from one generation to the next. Testing multiple markers gives us distinctive result sets. These sets form signatures for a paternal lineage. We compare your set of results to those of other men in our database. The range of possible generations before you share a common ancestor with a match depends on the level of test you take. A match may be recent, but it may also be hundreds of years in the past.
Over many generations, the number of repeats in each STR marker changes. The number of repeats may go up or down. These changes create the signatures for individual lines. This process is random. It is not possible to predict that any one marker will change between any set of generations. We do know though how often on average these random changes happen. Thus, we can estimate how closely related two men are by using the similarity of their results.
Your Ancestral Origins
Our Y-DNA marks the path from our direct paternal ancestors in Africa to their locations in historic times. Your ancestors carried their Y-DNA line on their travels. The current geography of your line shows the path of this journey. You can learn about the basics of your line’s branch on the paternal tree from your predicted branch placement. This information comes from scientists who study the history of populations across geography and time using Y-DNA. They use both the frequencies of each branch in modern populations and samples from ancient burial sites. With these, they are able to tell us much about the story for each branch. This traces back hundreds, thousands, or even tens of thousands of years. Your branch on the tree tells you where your paternal ancestors are present today and about their likely migration paths. This is your Y-DNA haplogroup.