Genetic Genealogy Basics
What is Genetic Genealogy?
Genetic genealogy is the science of using DNA testing alongside traditional genealogical methods to discover family relationships and ancestry. By analyzing variations in our DNA sequences, we can identify relatives, verify family connections, and explore our ethnic origins. This field combines the latest advances in genetic testing with traditional family history research methods to build more accurate and complete family trees.What are raw DNA files?
Raw DNA files are the unprocessed data from your DNA test, containing your genetic information in its most basic form. These files list the specific genetic markers (SNPs) tested and their values at each position. While DNA testing companies provide interpreted results, raw DNA files allow you to:1. Upload your genetic data to other services for additional analysis
2. Compare your DNA with potential relatives on different platforms
3. Access more detailed health and trait information through third-party tools
4. Preserve your genetic data independently of any single testing service
What are segment matches, and what do they tell us?
Segment matches are specific sections of DNA that you share with other tested individuals. When you match someone, you've inherited the same sequence of DNA at that location from a common ancestor. These matches provide several key pieces of information:▀▄ The length of the shared segment (measured in centimorgans or cM)
▀▄ The specific location of the match on which chromosome
▀▄ The estimated relationship range based on the amount of shared DNA
▀▄ Potential common ancestors within a certain number of generations
Longer segments generally indicate closer relationships, while shorter segments might represent more distant connections.
What is triangulation?
Triangulation is a powerful technique in genetic genealogy where you identify three or more people who share the same DNA segment and can trace their paper trails back to a common ancestor. This process helps:● Confirm that a DNA segment comes from a specific ancestral line
● Validate documentary research with genetic evidence
● Break through brick walls in traditional genealogical research
● Build confidence in proposed family relationships
To successfully triangulate, you need:
≡ At least three people sharing the same DNA segment
≡ Documentary evidence showing how these people connect
≡ The shared segment must be large enough to be significant (typically 7+ cM)
Why is DNA necessary for genealogy?
No amount of documentation can truly prove descent. Historical records can be incomplete, inaccurate, or even forged. DNA provides irrefutable biological evidence of shared ancestry, confirming connections and ensuring that the relationships in our family tree are scientifically validated.So what do I do with all of it?
I combine DNA results, segment matches, triangulation, and traditional genealogy research to piece together our family history. DNA helps confirm relationships hinted at by historical records, while records help narrow down potential shared ancestors identified through DNA. By combining these approaches, I can identify unknown ancestors and strengthen our family tree.Feel free to send me questions you might have or if you'd like to give me a copy of your DNA file!
