DNA Test 101 – What a DNA Test Actually Measures
Consumer DNA tests analyze hundreds of thousands of SNPs (genetic markers) to estimate where your ancestors may have lived and identify relatives who share segments of DNA.
Most ancestry tests are built on statistical models, large reference datasets, and how your DNA compares to anonymized population samples. These models improve over time but still have limits.
What DNA tests can tell you
- Ethnicity estimates based on reference populations
- Genetic relatives and shared DNA segments
- Some traits and health markers depending on provider
- Migration patterns and historical regions
What DNA tests cannot guarantee
- Exact percentages or precise locations
- Definitive medical diagnoses
- Perfect answers for underrepresented regions
- Unchanging results (updates happen)
For brand-by-brand breakdowns, see: Genectics.com – DNA test comparison .
Types of DNA Tests
Modern at-home DNA tests generally fall into three categories:
Ancestry Tests
Focus on ethnicity estimates and relative matching. Best for genealogy and family discoveries.
Health DNA Tests
Include selected genetic traits, carrier status, or risk markers depending on regulatory approval in your region.
Combined Tests
Offer both ancestry and health in one kit. Popular for people who want a broader overview in a single purchase.
How Accurate Are DNA Tests?
Accuracy depends on reference datasets, statistical models, database size and regional coverage. For well-sampled populations, accuracy is high. For smaller or under-sampled regions, results may be broader or updated over time.
Relative matching (finding cousins, parents, siblings) is usually the most accurate aspect of DNA testing and works extremely well across providers.
Genectics.com tracks accuracy differences across major DNA brands: Compare accuracy by provider .
DNA Test Privacy & Data Storage
Before taking a DNA test, consider how long companies store your DNA sample, how they handle deletion requests, and whether they partner with research organisations.
Privacy policies differ widely. Some companies delete your sample after processing, while others store it for future updates unless you request otherwise.
See the full privacy overview on: Genectics.com
Common Questions About DNA Tests
Can DNA tests identify unknown family members?
Yes. DNA databases grow quickly and make it possible to identify close and distant relatives even if they’ve never taken a test themselves.
Can DNA results conflict between companies?
Yes, because reference datasets and algorithms differ. Your ethnicity estimate may vary across providers, but close relative matches are typically consistent.
How long does processing take?
Usually 3–8 weeks after your sample reaches the lab. Peak seasons may take longer.
Ready to compare actual DNA tests?
TestDNA.bio helps you understand DNA testing before you buy anything. When you're ready to explore real kits, prices and accuracy, use the independent comparison tools at Genectics.com.