Understanding Your DNA Test Results
A Clear Guide to Reading and Interpreting DNA Test Reports
For many clients, receiving DNA test results can feel overwhelming, especially if this is your first experience with DNA testing. That is why we have created this comprehensive guide to help you understand what your DNA test results mean, how they are generated, and how to interpret them with confidence.
All DNA testing is performed at accredited laboratories using advanced scientific methods to ensure accurate, reliable results.
How DNA Testing Works
During DNA analysis, specific regions of DNA known as genetic loci are extracted, amplified, and analyzed using a laboratory process called PCR (Polymerase Chain Reaction). PCR allows scientists to work with very small amounts of DNA while maintaining extremely high accuracy.
Our laboratories analyze 23 or more STR loci, along with gender identification markers when applicable. These loci are compared between individuals to determine biological relationships or identify biological material.
How to Read a DNA Test Report
Your DNA test report is structured to clearly show how the DNA profiles were analyzed and compared.
Understanding DNA Loci and Alleles
Each locus represents a specific location on the DNA
For each locus, two numbers (alleles) are reported
One allele is inherited from the biological mother
The other allele is inherited from the biological father
For example, if a child’s DNA shows alleles 10 and 15 at a specific locus, one came from the mother and one from the father. If the alleged father also carries allele 15 at that locus, it supports biological inheritance.
By comparing DNA profiles across all tested loci, the laboratory can determine whether a biological relationship is supported or excluded.
Why Including the Mother’s Sample Helps
While a paternity test can be accurately completed without the mother’s DNA, including her sample is strongly recommended.
Adding the mother’s DNA:
Helps isolate the child’s paternal alleles
Strengthens statistical confidence
Can be essential in rare cases involving genetic mutations
Including the mother often results in clearer, more conclusive outcomes.
Understanding Relationship DNA Test Results
Paternity DNA Test Results
Paternity DNA Test results provide a clear inclusion or exclusion outcome.
Excluded: The alleged father does not share sufficient genetic markers with the child
Probability of paternity: 0%
Included: The alleged father shares the required genetic markers
Probability of paternity: 99.99% or higher
These results are considered scientifically conclusive.
View Example Paternity DNA Test Results
Sibling and Other DNA Relationship Test Results
Sibling DNA Testing, Grandparent DNA Testing, Avuncular DNA Testing, and other relationship DNA tests are based on statistical probability, not absolute inclusion or exclusion.
Possible outcomes include:
The tested relationship is supported
The tested relationship is not supported
The result is inconclusive
Understanding the Likelihood Ratio and Probability
Relationship DNA tests use two key values:
Likelihood Ratio (LR)
Less than 1.0: Relationship is unlikely
Greater than 1.0: Relationship is more likely than not
Higher values indicate stronger support
Probability Percentage
Based on inheritance patterns, the laboratory calculates the probability that the tested individuals share a biological relationship.
According to AABB standards:
90.9% or higher: Conclusive support for a relationship
10%–90.8%: Inconclusive
Below 10%: Relationship not supported
How to Increase the Chance of a Conclusive Result
The most effective way to strengthen relationship DNA test results is to include additional known relatives to any of the participants, most commonly the biological mother.
Including a known parent:
Increases statistical power
Reduces inconclusive outcomes
Provides clearer interpretation
View Example Relationship DNA Test Results
Understanding Infidelity DNA Test Results
Infidelity DNA testing results vary depending on the type of test performed.
Semen Detection Test Results
Semen Detection testing identifies the presence of semen by detecting semenogelin, a human-specific protein found in seminal fluid.
Semenogelin testing is widely used in forensic science because it:
Is highly sensitive
Does not cross-react with other substances
Reduces the risk of false positives
Possible results:
Positive: Semen was detected
Negative: Semen was not detected
View Example Semen Detection Test Results
DNA Extraction and Comparison Results
DNA Extraction and Comparison Testing goes beyond semen detection by analyzing the DNA found in a stain or sample.
This process may include:
Determining whether DNA is male, female, or a mixture
Comparing recovered DNA to a reference cheek swab
Ruling out DNA belonging to the client
Comparing DNA to a known partner sample, if provided
The final report includes:
DNA profiles for each sample
A written interpretation of findings
Match or non-match conclusions
Reference profiles used for comparison
View Example Infidelity DNA Test Results
Need Help Understanding Your Results?
DNA test results can raise questions, especially in sensitive situations. Our experienced DNA experts are available to help explain your results and discuss next steps.
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