Paternity testing: what to know before you book
A DNA paternity test is a cheek swab and a wait. The complicated part is deciding which kind of test you need, because a result that settles a private question and a result a judge will accept are two different products at two different prices.
How the test actually works
Everyone inherits half of their DNA from each biological parent. Laboratories compare specific locations in the genome called short tandem repeats, or STRs - stretches of DNA where a short sequence repeats a variable number of times. At each location the child has two values, one from each parent. The lab checks whether the value that did not come from the mother is present in the alleged father.
Miss even one marker pair and the man is excluded. Match across 20 or more markers and the lab calculates a combined paternity index, which is reported as a probability of paternity, typically 99.9% or greater. The National Library of Medicine's MedlinePlus has a good primer on how genetic testing is performed and reported.
Legal test vs. at-home kit
This is the single decision that determines where you go and what you pay. The laboratory science is identical. What differs is whether anyone can prove the samples came from the people named on the report.
| Legal (court-admissible) | At-home kit | |
|---|---|---|
| Typical cost | $300–$500 | $80–$200 |
| Who collects | Neutral third party at a collection site | You, at home |
| ID required | Photo ID for adults, birth certificate for the child | None |
| Chain of custody | Documented end to end | None |
| Accepted by courts | Yes | No |
| Accuracy of the result | Same | Same |
A useful rule: if the answer is only for you, an at-home kit is fine. The moment the answer will be shown to a court, a child support agency, a vital records office, or an immigration officer, you need the legal version, and you cannot upgrade an at-home result after the fact. You have to test again.
Why accreditation matters
For anything official, the laboratory must be accredited for relationship testing - in the United States that effectively means accreditation by AABB, which publishes a searchable list of accredited relationship-testing facilities. Courts, state child support agencies, and U.S. Citizenship and Immigration Services all rely on that accreditation as their quality floor. A storefront that collects your swab is usually not the lab; ask which accredited laboratory the sample is shipped to.
Where you can get tested
- Accredited DNA testing centers - dedicated paternity providers that handle legal, at-home, prenatal, and immigration testing.
- Walk-in lab storefronts (Any Lab Test Now, ARCpoint Labs, Health Street) - no doctor's order needed, same-day collection in many locations.
- LabCorp and Quest patient service centers - act as collection sites when an accredited lab schedules the appointment.
- Hospital laboratories - sometimes used for court-ordered collections; may require a physician order.
- At-home kits - ordered online, swabbed in private, mailed back to the lab.
Use the directory to find any of these near you, or open the map.
A DNA result is not the same as legal fatherhood
This trips up almost everyone. A test tells you biology. Legal fatherhood - the status that carries custody rights, child support obligations, inheritance, and a name on the birth certificate - is established separately, usually by signing a voluntary Acknowledgment of Paternity at the hospital or afterward, or by court order. The federal Office of Child Support Services explains how paternity establishment works and how it connects to the state child support system.
Every state also runs its own rules on time limits, presumptions of paternity for married couples, and how to correct a birth certificate. Our state-by-state guides cover those.
Other tests people ask about
- Prenatal (NIPP) - a blood draw from the mother from about week 7, no risk to the pregnancy.
- Immigration DNA - used to support a family relationship in a visa or citizenship petition; must be arranged by an AABB-accredited lab and sent directly to the government.
- Sibling, grandparent, and avuncular tests - used when the alleged father is unavailable or deceased. These give probabilities rather than near-certainty, so more relatives tested means a stronger answer.
- Y-STR testing - checks whether two males share a paternal line, but cannot distinguish between a father, a brother, or a paternal uncle.
Frequently asked questions
How accurate is a DNA paternity test?
When the alleged father is the biological father, modern tests typically report a probability of paternity of 99.9% or higher. When he is not, the test excludes him with 100% certainty. Accuracy comes from comparing 20 or more short tandem repeat (STR) markers, and it does not depend on whether the test is a legal one or an at-home kit.
What is the difference between a legal test and an at-home test?
The laboratory analysis is identical. The difference is chain of custody: a legal test requires a neutral third party to verify each person's identity with photo ID, photograph them, collect the samples, and document the sample's handling all the way to the lab. That paperwork is what makes the result admissible in court. An at-home kit that you swab yourself has no such documentation, so no court or government agency will accept it.
How much does a paternity test cost?
At-home kits generally run about $80 to $200 including lab fees. A legal, court-admissible test usually runs about $300 to $500 for an alleged father and one child, because it includes a witnessed collection appointment and documented chain of custody. Prenatal (non-invasive) paternity testing is the most expensive, commonly $1,300 to $2,000.
Do you need the mother's DNA for a paternity test?
Usually no. A standard test compares the child and the alleged father, and that is enough to produce a conclusive result in nearly all cases. Including the mother's sample can strengthen the statistics in unusual cases, such as when close relatives of the alleged father are also possible fathers.
How long do results take?
Most laboratories report standard results in 1 to 3 business days after the samples arrive, with expedited options available. Legal tests can take slightly longer because the report is reviewed and often mailed to the court or attorney as well.
Can a paternity test be done before the baby is born?
Yes. Non-invasive prenatal paternity testing (NIPP) uses cell-free fetal DNA in a sample of the mother's blood and can be done from around the seventh to ninth week of pregnancy, with no risk to the pregnancy. The older invasive methods (amniocentesis and CVS) carry a small risk of miscarriage and are not performed for paternity reasons alone.
Does a DNA test automatically put a father on the birth certificate?
No. A DNA result is evidence, not a legal status. Depending on the state, legal fatherhood is established by signing a voluntary Acknowledgment of Paternity, by a court order, or by a marital presumption. Amending the birth certificate is a separate step handled by the state vital records office.
This page is general information, not legal or medical advice. Rules vary by state and change over time; confirm requirements with the court or agency involved and, where a case is contested, with an attorney licensed in your state.