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How DNA Comparison Testing Works

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Quick Answer: What Is DNA Comparison Testing?

DNA comparison testing analyzes genetic profiles from two or more samples to determine whether they match or are biologically related. This type of testing is commonly used to compare DNA found on items to known reference samples.

What Is DNA Comparison Testing?

DNA comparison testing is a laboratory process used to determine whether two or more DNA samples are from the same individual or share a biological relationship.

This type of testing is commonly used when biological material is found on an item and needs to be compared to a known individual.

For example, DNA recovered from clothing or other personal items may be compared to a reference sample to determine whether there is a match.

Learn more about how DNA can be found on items here: How DNA Gets on Clothing.

How DNA Comparison Testing Works

DNA comparison testing involves several steps.

1. DNA Extraction

Biological material such as skin cells or bodily fluids is collected from the item being tested. DNA is then extracted from the collected material.

2. DNA Profiling

The laboratory analyzes specific genetic markers in the DNA to create a DNA profile for each sample.

3. Profile Comparison

The DNA profile from the evidence sample is compared to the DNA profile of the reference sample.

4. Result Interpretation

Scientists evaluate whether the genetic markers match and determine whether the samples are consistent with originating from the same individual or a biological relationship.

What Does a DNA Match Mean?

A DNA match means that the genetic markers in two DNA profiles are consistent with coming from the same individual or from individuals who share a biological relationship.

If the profiles do not match, the laboratory can determine that the samples did not originate from the same person.

What Happens If Multiple DNA Profiles Are Found?

In some cases, more than one DNA profile may be detected in a sample. This is known as a mixed DNA sample.

Mixed samples can occur when biological material from multiple individuals is present on the same item.

Laboratories analyze these samples to determine:

  • how many contributors may be present

  • whether a specific individual can be included or excluded

Learn more about mixed DNA samples here: What Happens if Multiple DNA Profiles are Found?

Factors That Affect DNA Comparison Results

Several factors can influence DNA comparison testing.

Quality of the Sample

Degraded or limited DNA may make analysis more difficult.

Quantity of DNA

Very small amounts of DNA may not produce a complete profile.

Mixed Samples

The presence of multiple contributors can complicate interpretation.

Environmental Exposure

Heat, moisture, and time can degrade DNA.

How DNA Comparison Testing Is Used

DNA comparison testing is used in a variety of situations.

Common uses include:

  • comparing DNA from clothing or personal items

  • evaluating biological evidence

  • determining whether two samples may come from the same individual

  • supporting relationship testing in certain cases

This type of testing is often used alongside biological fluid detection testing.

DNA Comparison vs Relationship Testing

DNA comparison testing and relationship DNA testing are related but serve different purposes.

DNA comparison testing

  • compares unknown DNA to a known sample

  • determines whether samples match

Relationship DNA testing

  • compares known individuals

  • determines biological relationships such as paternity or siblingship

Learn more about relationship DNA testing here: Relationship DNA Testing Explained.

Understanding DNA Comparison Testing

DNA comparison testing provides a scientific method for evaluating whether biological material from different samples may be related or originate from the same individual. By analyzing genetic markers and comparing DNA profiles, laboratories can provide valuable information about biological evidence.

Understanding how this process works helps individuals interpret results and better understand what DNA testing can reveal.

Cited References:

Validity Genetic Services

WHAT KIND OF SAMPLES DO I NEED TO PROVIDE?

We primarily use simple oral buccal swabs (cheek cell collection) to collect samples for our quick easy home and legal DNA tests.

Validity Genetics can test from a variety of other types of samples. However, in these cases an extra fee may apply as well as a possible longer turnaround time for sample processing.

How fast can I get my results?

Validity Genetics offers a quick turnaround time of only two business days once received at the lab for all of our standard buccal swab DNA collection tests. We also have rush options available if needed (may not available on some special sample types such as Infidelity Testing).

How accurate are the tests?

Our procedures test for 22 genetic markers and the gender identification marker amelogenin. This ensures you receive 99.99% accurate test results.

A general principle for DNA testing is that the more genetic information available, the greater the precision of the test.

All of Validity Genetics' genetic testing services follow strict and validated procedures for processing samples to guarantee the utmost care of your samples.

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