Understanding Autosomal DNA Testing
My AncestryDNA results arrived, revealing a 200 cM match—a 3rd cousin who shared a 1900s photo. Autosomal DNA testing is the most popular tool for genealogy, tracing all ancestral lines. This guide explains how it works, how to use results, and why it’s perfect for beginners. Start your journey with our Getting Started with DNA Testing.
What Is Autosomal DNA Testing?
Autosomal DNA testing analyzes chromosomes 1–22, inherited from both parents, making it ideal for tracing all family lines. My MyHeritage test showed 25% Sicilian roots, confirmed by FamilySearch. It’s the go-to test for beginners, costing $59–$99, offering ethnicity and cousin matches.
How Autosomal DNA Works
You inherit half your autosomal DNA from each parent, mixed randomly from their ancestors. Tests compare your DNA to others, measuring shared segments in centimorgans (cM). My 150 cM match was a 3rd cousin, verified by a 1900 census. This broad approach suits beginners exploring multiple branches.
Key Benefits
- Broad Ancestry: Traces all family lines, unlike mtDNA or Y-DNA.
- Cousin Matching: Finds relatives from 1st to distant cousins.
- Ethnicity Estimates: Reveals origins like 30% Scandinavian.
How Autosomal Testing Finds Matches
Matches are relatives sharing DNA, measured in cM. A 500 cM match might be a 1st cousin, while 20 cM suggests a 5th cousin. My AncestryDNA 200 cM match led to an Irish cousin, confirmed by FamilySearch. Tools like GEDmatch enhance matching.
Understanding Centimorgans
Centimorgans measure shared DNA length. For example, siblings share ~2600 cM, 1st cousins ~850 cM. My 20 cM match required tree-building to confirm a 5th cousin. Beginners should learn cM ranges to estimate relationships.
Match Categories
- Close Matches (50+ cM): Likely 1st–3rd cousins; contact them first.
- Distant Matches (20–50 cM): Need tree-building to verify.
- Shared Matches: Show connections between relatives.
Using Autosomal Test Results
Autosomal results include ethnicity estimates and matches. My MyHeritage test refined my Sicilian roots, while AncestryDNA’s ThruLines suggested a 3rd cousin. Tools like GEDmatch offer cross-platform analysis.
Key Tools
- AncestryDNA: ThruLines for relationship suggestions.
- MyHeritage: Theory of Family Relativity for record links.
- GEDmatch: Free triangulation tool.
Maximizing Results
- Upload to GEDmatch. See our GEDmatch Tutorial.
- Build a tree on Ancestry.
- Cross-check with FamilySearch.
Common Mistakes to Avoid
Beginners often misread cM or ignore small matches. I assumed a 100 cM match was a 2nd cousin, but GEDmatch showed it was a 4th cousin. Not building a tree delayed my discoveries.
Pitfalls
- Misinterpreting cM values.
- Ignoring distant matches.
- Not linking results to a tree.
Success Stories
Autosomal testing creates breakthroughs. These stories inspire beginners.
- Emma: Found a Polish cousin via AncestryDNA.
- John: Traced German roots on MyHeritage.
- Maria: Linked to a French cousin via GEDmatch.
- Tom: Uncovered Irish ancestry on 23andMe.
Next Steps
Start your autosomal DNA journey with these steps to uncover your heritage.
- Test with AncestryDNA.
- Build a tree with our Family Tree Guide.
- Join Reddit r/Genealogy.
- Share on our About Page.