About the Test
Purpose of the test
The purpose of a paternity test is to determine whether someone is the genetic parent of a child. A paternity test may be taken for a variety of reasons, including:
- Legal purposes: Legal paternity testing involves testing ordered by a court. For the results of a paternity test to be used as evidence in court, the test must be conducted with oversight and documentation of each step.
- Resolving uncertainty: If there is uncertainty about a child’s genetic parents, paternity testing may be used to confirm the identity of a child’s genetic parent, provide information about the child’s lineage and family history, and offer reassurance or peace of mind about genetic relationships.
- Medical purposes: Although not a common use for paternity testing, confirming the identity of a child’s genetic parent can provide information about the child’s family health history.
What does the test measure?
Modern paternity testing typically compares the DNA of a child to the DNA of the potential genetic parent or parents.
DNA, or deoxyribonucleic acid, is the genetic code found in the cells of most living organisms. DNA is hereditary, meaning that it is passed from parent to child. A child’s DNA is a combination of both parents’ DNA. Almost every cell in a person’s body contains that individual’s same hereditary DNA.
DNA paternity testing identifies distinct features in samples of a child’s DNA and compares them to features found in the DNA of a potential genetic parent. If these features are present in both the parent and child’s DNA, this indicates a strong likelihood that the two are genetically related. If common features are not found, a genetic relationship can be virtually ruled out. In some cases, a child’s DNA is compared to the DNA of both genetic parents to provide increased accuracy of test results.
Other methods of paternity testing involve comparing blood types and HLA types. Because DNA testing is more accurate, these methods are rarely used.
When should I get a paternity test?
Paternity testing may be called for when the identity of a child’s genetic parent is unknown or disputed.
Legal paternity testing may be used when there is a need to legally confirm a genetic relationship. Legal paternity testing may be ordered for many reasons, including:
- Adding a parent’s name to a child’s birth certificate
- Addressing issues during court cases related to child support, child custody, or parental visitation rights
- Establishing citizenship for a child born overseas
- Obtaining an immigrant visa
- Helping a child gain access to certain government benefits
- Clarifying issues of inheritance
People may voluntarily choose to take a paternity test for several reasons, including:
- Confirming that someone is not the genetic parent of a child
- Helping a child learn more about their genetic parents and ancestry
- Gathering information about a child’s family medical history
- Resolving curiosity, obtaining reassurance, or providing peace of mind about genetic relationships
Finding a Paternity Test
How to get tested
How to find a paternity test depends on whether the results will be used in legal proceedings. For the results of a paternity test to be used as evidence in court, the test must be conducted with specific oversight and documentation of each step. Laboratories and companies often refer to this process as a legal paternity test.
States may have different requirements for legal paternity testing. Generally, you will need to have your sample collected at a certified collection site. The collection process will also need to be observed by an impartial witness. The mother, child, and possible father usually have their test samples taken at different times. If a court or state agency has ordered a test, they may refer you to a specific laboratory or collection site.
If you wish to obtain a non-legal paternity test, you can contact a testing company or laboratory directly for information about the nearest collection site or the availability of at-home paternity testing kits.
Can I take the test at home?
Many companies offer at-home DNA paternity testing. With an at-home paternity test, you collect the test sample and mail it to a laboratory for analysis. Samples used for testing involve cheek swabs taken from the child and one or both potential genetic parents.
Some at-home paternity test kits may be purchased at pharmacies or drug stores. You may also be able to order collection kits directly from a testing company over the phone or online.
At-home paternity tests may use the same testing procedures as legal tests. However, the results of at-home testing generally cannot be used as evidence in court because there is no way to prove exactly who provided the DNA samples.
How much does the test cost?
The cost of paternity testing can depend on several variables, such as who performs the test and whether the test is court-ordered.
Legal paternity tests are generally more expensive than at-home tests because of the need for witnesses and documentation. Taking a legal paternity test may also require paying for related court costs.
If a state agency or court orders paternity testing, they may cover the costs of the test. However, this varies from state to state. In some cases, a person may be required to pay for testing if they are confirmed to be the child’s genetic parent.
At-home paternity tests may involve two sets of costs: one set for the test collection kits and another for the laboratory fees to analyze the samples. The laboratory fees may be several times higher than the cost of the kits. Some at-home tests may come with the laboratory costs included.
Because a paternity test is not considered medically necessary, it is typically not covered by a person’s health insurance.
Taking a Paternity Test
Samples of DNA used for paternity testing are most often obtained by swabbing the inside of the cheeks. While blood samples can also be used, blood draws are more intrusive and less convenient. Also, because a person’s DNA is the same in cells that line the cheeks and in blood cells, a cheek swab is just as accurate as a blood test.
Some types of paternity testing can be done during pregnancy. One method, called non-invasive prenatal paternity testing, uses a sample of the mother’s blood to identify cell-free fetal DNA (cfDNA) that can be compared to the other genetic parent’s DNA. Prenatal paternity testing can also be performed through amniocentesis and related procedures, but these methods can pose risks to both the mother and baby.
For prenatal paternity testing, samples from the baby and pregnant parent are collected in a clinical or hospital setting. The possible genetic parent’s sample can be obtained through a cheek swab.
Before the test
There are typically no pre-test instructions before obtaining a cheek swab or blood sample for paternity testing. If you are taking a court-ordered legal paternity test, you may need to bring a picture ID with you to the testing site. You may also need to sign documents and have your photograph taken.
If you are taking an at-home test, the testing company will send you collection kits for each person’s sample, a return envelope, and instructions. You may need to register through the company’s website in order to receive results.
During the test
During a cheek swab, you may be asked to begin by rinsing your mouth. A long swab or scraper is used to collect cells from the inside of your cheek. This may be performed by a medical professional, or you may be asked to swab your cheek yourself. A cheek swab is typically painless and takes only a few minutes.
If you are providing a blood sample, it will be taken through a needle from a vein in your arm. A medical professional called a phlebotomist will tie a band around your upper arm to make the vein more prominent. Then they will disinfect the skin and insert the needle. You may feel a slight sting when the needle goes in and comes out, but the whole procedure normally takes just a few minutes.
If you are taking an at-home paternity test, you will swab the inside of your cheek yourself. The testing company may send you several swabs to collect multiple samples. Be sure to follow the test instructions carefully.
After the test
There are no post-test instructions following a cheek swab, so you can go about your normal activities.
When a blood draw is finished, the phlebotomist will cover the puncture site with a small bandage or cotton swab. You may need to keep this in place for up to an hour.
Once the cheek swab or blood collection is complete, the sample is sent to a laboratory for analysis.
Paternity Test Results
Receiving test results
Many factors can influence how long it may take to get paternity test results. If you are taking an at-home test, results may be ready in a matter of days, but this can depend on the time required to send samples to the laboratory through the mail.
The laboratory or testing company may make the results of paternity testing available through an online portal. If the testing company performed a legal test, you may receive results in the mail as well.
The results of a legal paternity test may take several weeks or longer. If testing is done through a state agency, that agency may mail you the results and documentation for use in court.
Interpreting test results
The results of a DNA paternity test show how likely someone is to be the biological father or genetic parent of a child. On a test report, this is often called the probability of paternity. The probability of paternity is generally described as one of two values: 0 or 99.99.
If the probability of paternity is 0, the report may state that the subject is “excluded” as the genetic parent. If the probability is 99.99 or greater, it may state that the subject is “not excluded.”
A probability of 0 means that the paternity test has ruled out the test subject as a possible genetic parent. A probability of 99.99 or higher means that the test subject is extremely likely to be the child’s genetic parent.
Are test results accurate?
While no test is perfect, DNA paternity testing is considered to be highly accurate. Results of DNA paternity testing are 99-100% accurate in determining whether someone is the child’s genetic parent.
Do I need follow-up tests?
Follow-up tests are usually not necessary after taking a paternity test. In some legal cases, a second paternity test may be needed if one of the parties disputes the results of the first test.
Questions for your doctor about test results
Although a doctor isn’t always involved in ordering or taking a paternity test, it may be helpful to discuss questions or concerns about paternity testing with a medical and/or legal professional. Helpful questions may include:
- Can you help me understand the results of a paternity test?
- Are the results of this paternity test admissible in court?
