A paternity test requires a DNA sample from the child and the possible father, and in many cases, a sample from the mother as well. The standard method used by nearly all labs today is a cheek swab, where a small brush or cotton tip is rubbed along the inside of the mouth to collect cells. No blood draw, no needles, no pain. Beyond the physical sample, what else you need depends on whether you’re testing for personal knowledge or for a result that holds up in court.
The DNA Sample Itself
The cheek swab (sometimes called a buccal swab) has almost entirely replaced blood draws for paternity testing. The procedure takes about 30 seconds per person: you rub the swab firmly against the inside of your cheek, seal it in a provided envelope, and that’s it. The cells collected from the cheek lining contain the same DNA as a blood sample, and labs can extract a full genetic profile from them with no loss in accuracy.
Most labs will ask for samples from three people: the child, the alleged father, and the mother. The mother’s sample isn’t strictly required, but including it strengthens the result by allowing the lab to isolate which half of the child’s DNA came from each parent. When the mother’s sample is included, the probability of paternity on a positive result is typically 99.99% or higher.
To avoid contaminating the sample, you should not eat, drink, smoke, or chew gum for at least 30 minutes before swabbing. These activities can introduce foreign material that interferes with DNA extraction.
Home Test vs. Legal Test
This is the single biggest distinction in paternity testing, and it determines what paperwork and procedures you’ll need.
A home (or “peace of mind”) test is the simpler option. You order a kit online or buy one at a pharmacy, collect the cheek swabs yourself at home, and mail them to the lab. No witnesses, no ID verification, no appointments. The result tells you whether the tested man is the biological father, but it cannot be used in court for child support, custody, or any other legal proceeding. It’s for personal knowledge only.
A legal paternity test produces a court-admissible result, and that requires what’s called a chain of custody. This means every step of the collection process is documented and witnessed to prove the samples weren’t tampered with or swapped. For a legal test, you’ll need to go to a designated collection site, typically a lab, clinic, or medical office, where a trained collector will:
- Verify your identity using government-issued photo ID such as a driver’s license or passport
- Photograph each participant so the samples are linked to confirmed individuals
- Collect the swabs directly while you’re present, sealing and labeling them on site
- Have all parties sign consent forms authorizing the test
For children, a parent or legal guardian signs the consent form on their behalf. Some labs require verbal agreement from older children as well. Courts that order paternity tests will schedule the appointment for you and receive the results directly from the lab.
What the Lab Analyzes
Modern paternity labs compare your DNA at 21 or more specific genetic markers. At each marker, a child inherits one copy from the mother and one from the father. The lab checks whether the alleged father’s DNA matches the paternal half at every single marker. If the profiles match across all tested locations, the result confirms paternity. If multiple markers don’t match, the man is excluded as the biological father.
Labs that handle legal cases in the United States are typically accredited by the AABB (formerly the American Association of Blood Banks), which sets the technical and procedural standards for relationship testing. AABB accreditation is also required for DNA tests used in immigration cases processed by U.S. Citizenship and Immigration Services.
Testing During Pregnancy
You don’t have to wait until the baby is born. A non-invasive prenatal paternity test can be performed as early as the 7th week of pregnancy. It works by drawing blood from the mother, which contains fragments of the baby’s DNA circulating in her bloodstream. The possible father still provides a standard cheek swab. The lab then compares the fetal DNA against the father’s profile.
This test carries no risk to the pregnancy because it only requires a maternal blood draw, not a needle into the uterus. Older methods like amniocentesis and chorionic villus sampling (CVS) can also establish paternity but involve a small risk of miscarriage. Most people choosing prenatal testing now opt for the non-invasive blood draw.
When the Father Isn’t Available
If the alleged father is deceased, missing, or unwilling to test, you can still establish a biological link through his relatives. Several alternative tests exist depending on who is available:
- Grandparentage test: requires one alleged grandparent (the father’s parent) and the child
- Avuncular test: requires one alleged aunt or uncle (the father’s sibling) and the child
- Siblingship test: compares two alleged siblings, ideally with the mother’s sample included
- Y-chromosome test: compares two males to determine if they share a paternal lineage
These indirect tests are less definitive than a standard paternity test because the relatives share some but not all of the alleged father’s DNA. Including the mother’s sample significantly improves accuracy. Results are reported as a probability of relatedness rather than a near-certain yes or no.
Cost and Turnaround Time
Home paternity test kits generally cost between $100 and $200, with the kit itself sometimes available for under $100 and a separate lab processing fee on top. Legal tests run higher, typically $300 to $500 or more, because of the chain-of-custody collection process and additional documentation. Prenatal tests are the most expensive, often ranging from $1,500 to $2,000 due to the complexity of isolating fetal DNA from a maternal blood sample.
Results from a standard cheek-swab test usually arrive within 3 to 5 business days after the lab receives your samples. Some labs offer rush processing for an additional fee, delivering results in 1 to 2 business days. Prenatal results may take slightly longer. If your test was ordered by a court, the results go to the court first and are explained to both parties at the next hearing date.