What Can Be Used for DNA Testing?
When considering DNA testing, one of the most common questions is: What types of samples can be used for a DNA test?
While a simple cheek swab is the preferred method for most DNA tests, it isn't the only option. Many everyday items, including toothbrushes, hair with roots, clothing, and dried biological stains, may contain DNA suitable for laboratory analysis.
The best sample depends on the type of testing needed, whether the individual can provide a cheek swab, and the condition of the available material.
At Validity Genetics, we offer standard DNA testing using oral swabs as well as specialized forensic DNA testing using non-standard samples.
Here's a closer look at the most common types of DNA samples, how they are used, and what to consider before submitting an item for testing.
Standard DNA Samples: Why Cheek Swabs Are Preferred
For most relationship DNA tests, an oral cheek swab, also called a buccal swab, is the recommended collection method.
A cheek swab is gently rubbed against the inside of the mouth to collect cells containing DNA. The process is painless, noninvasive, and generally takes only a few minutes.
Cheek swabs are preferred because they typically provide a reliable source of DNA with a lower risk of contamination or mixed profiles than many personal items.
They are commonly used for:
For most people seeking to establish a biological relationship, a standard cheek swab is the simplest and most reliable starting point.
What Are Forensic or Non-Standard DNA Samples?
When a cheek swab is unavailable, laboratories may be able to recover DNA from other biological materials or personal items.
These are known as forensic or non-standard DNA samples (NSS).
Non-standard samples may be used when an individual is deceased, unavailable, or cannot provide a conventional cheek swab.
They are also commonly used in Infidelity DNA Testing to examine clothing, bedding, or other items for biological material.
Unlike directly collected cheek swabs, forensic samples may contain limited, degraded, or mixed DNA. Additional laboratory processing is often required, and successful DNA recovery cannot be guaranteed.
Validity Genetics offers several specialized Forensic Relationship DNA Testing services for situations where traditional DNA sample collection is not possible.
Common Types of Forensic DNA Samples
1. Toothbrushes
Used toothbrushes are among the more useful non-standard samples for relationship DNA testing.
They often contain oral epithelial cells deposited during regular brushing, making them a potential source of DNA from the person who uses the toothbrush.
A toothbrush used exclusively by one individual is generally preferable to an item that may have been handled or used by several people.
Toothbrushes are frequently considered for Forensic Paternity DNA Testing when the alleged father is unavailable or unable to provide a cheek swab.
2. Hair With Roots
Hair may be suitable for DNA testing when the strands contain attached roots or follicular tissue.
For conventional nuclear DNA profiling, we generally recommend submitting approximately 4–9 strands of hair with visible roots, when available.
Hair that has been cut or naturally shed without suitable root material is less likely to produce the nuclear DNA needed for standard relationship testing.
If hair is the only available sample, contact us before ordering so we can help determine whether it is suitable for the requested analysis.
3. Dried Bloodstains
Bloodstains may provide a useful source of DNA when sufficient biological material is present.
Common examples include stained clothing, bandages, tissues, or other absorbent materials.
Dried bloodstains can sometimes remain suitable for testing for extended periods, particularly when protected from moisture, excessive heat, and sunlight.
Validity Genetics also offers specialized blood detection testing when the goal is to determine whether a suspicious stain contains human blood.
4. Saliva Stains
Saliva may contain cells from the inside of the mouth that can provide DNA for laboratory analysis.
Potential sources include used tissues, cigarette butts, chewing gum, and certain personal items.
However, items such as drinking glasses, cups, and utensils may contain DNA from multiple people, making them less desirable than a cheek swab or personal toothbrush.
When the goal is to determine whether a stain contains saliva, specialized saliva detection testing may be more appropriate than DNA profiling alone.
5. Fingernail Clippings
Fingernail clippings may contain recoverable DNA, although the quantity and quality can vary.
Multiple clippings may be needed, and successful profiling is not guaranteed.
As with other non-standard samples, contamination and mixed DNA can complicate testing.
If fingernail clippings are your only available sample, we recommend contacting us before submitting them.
6. Clothing and Biological Stains
Clothing, underwear, bedding, and other fabrics may contain biological material such as semen, saliva, blood, or skin cells.
These items are commonly submitted for infidelity DNA testing, although they may also be useful in certain forensic relationship cases.
Whenever possible, identify the specific stain or area of concern rather than requesting testing across an entire garment.
For example, testing a visibly stained area of underwear may be more informative than randomly sampling multiple areas of the same item.
Depending on what you are trying to determine, Validity Genetics offers several testing options:
Semen Detection Testing to determine whether human semen is present.
Simple Infidelity DNA Testing to attempt to recover and report human DNA profiles.
Advanced Infidelity DNA Testing to extract DNA and compare recovered profiles against a known reference sample.
Complete Infidelity DNA Testing to combine semen detection with DNA extraction and comparison.
For detailed instructions, read our guide on How to Collect DNA Samples for Infidelity Testing.
7. Teeth
Teeth can sometimes provide DNA when other sample types are unavailable.
However, tooth testing requires specialized laboratory procedures and may involve additional processing time and costs.
Not all teeth are equally suitable, and the condition of the tooth can affect DNA recovery.
Teeth may be considered in certain forensic relationship investigations, including cases involving deceased or unavailable individuals.
We do offer a specialized Paternity test using teeth, Forensic Paternity DNA Test - Teeth.
What Makes a Good DNA Sample?
Regardless of the sample type, successful DNA testing depends on the amount and quality of recoverable DNA.
The most useful samples generally have:
Sufficient biological material
Minimal handling or contamination
Limited exposure to heat, moisture, or sunlight
Proper collection and storage
A clear connection to the individual being tested
One important consideration is whether the item contains DNA from only one person.
For example, a toothbrush used by one individual may provide a more straightforward profile than a shared towel or drinking glass.
A sample containing DNA from multiple contributors may be more difficult to interpret, particularly for relationship testing.
Can Old DNA Samples Still Be Tested?
Yes. DNA may remain recoverable from older samples, sometimes even after months or years.
However, there is no guaranteed period during which every sample remains suitable for testing.
DNA stability depends on the material, environmental exposure, and storage conditions.
For best results, keep samples dry, avoid unnecessary handling, and protect them from excessive heat and sunlight.
If an item is wet or damp, allow it to air dry before packaging. Whenever possible, use a paper envelope or paper bag rather than placing biological material directly into plastic.
What Happens If a Forensic Sample Does Not Contain Enough DNA?
Not every non-standard sample produces a usable DNA profile.
The laboratory may encounter insufficient DNA, degraded genetic material, contamination, or a mixture involving multiple individuals.
In these situations, additional analysis or a different sample may be necessary.
If you're considering a forensic DNA test, choosing the most suitable available item before ordering can help reduce unnecessary testing and improve the likelihood of obtaining informative results.
Frequently Asked Questions About DNA Samples
What is the best sample for DNA testing?
A cheek swab collected directly from the individual is generally the preferred sample for standard paternity and relationship DNA testing. It is simple to collect and typically provides a reliable source of DNA.
Can a toothbrush be used for a paternity DNA test?
Yes. A used toothbrush may provide recoverable DNA for forensic paternity testing when a conventional cheek swab is unavailable.
A toothbrush used exclusively by the individual being tested is generally preferred, although successful DNA recovery cannot be guaranteed.
Learn more about Forensic Paternity DNA Testing.
Can hair be used for DNA testing?
Yes. Hair with attached roots or follicular tissue may provide nuclear DNA suitable for testing.
Cut hair or hair without suitable roots is generally less useful for conventional relationship DNA analysis.
Can clothing be tested for DNA?
Yes. Clothing may contain biological material suitable for DNA extraction, particularly in stained areas.
Depending on the circumstances, testing may detect human DNA or biological material such as semen, saliva, or blood.
However, the presence of recoverable DNA is not guaranteed.
Can DNA testing be performed using an old sample?
Possibly. Some older samples remain suitable for testing, depending on the type of material and how it has been stored.
Dry samples protected from heat, moisture, and sunlight generally have a better chance of preserving usable DNA.
Can multiple people's DNA be found on one item?
Yes. Shared or frequently handled items may contain DNA from multiple individuals.
These mixed DNA profiles can make analysis more complex, especially when attempting to establish a biological relationship or compare DNA recovered from an item to a known person.
Can DNA testing determine who touched or used an item?
DNA testing may establish whether a recovered DNA profile is consistent with a known person's reference profile.
However, the presence of DNA does not necessarily prove that someone directly touched or used an item. DNA can sometimes be transferred indirectly through contact with other people or objects.
DNA testing also cannot reliably determine when the DNA was deposited.
Choosing the Right DNA Sample for Your Test
For most paternity and relationship DNA tests, a standard cheek swab remains the preferred option.
However, when a conventional sample cannot be obtained, forensic DNA testing may offer an alternative using suitable personal items or biological evidence.
At Validity Genetics, we offer both standard and forensic DNA testing options, including Forensic Paternity, Forensic Sibling, Forensic Avuncular, and Forensic Grandparent DNA Testing.
If you're unsure whether a toothbrush, hair sample, clothing item, or another material is suitable, contact Validity Genetics before ordering.
Our team can help you understand your sample options and determine which testing method may be most appropriate for your situation.
