A DNA paternity test comes back one of two ways. An inclusion result shows a probability of paternity of 99.99% or higher, which labs and courts treat as confirmation that the tested man is the biological father. An exclusion result shows 0%, meaning there is no genetic match. Those two outcomes drive everything that follows: child support, custody and visitation, and the child’s eligibility for benefits like Social Security. DNA paternity test results carry this weight only when the testing meets certain standards, so understanding what the numbers mean and how the test was conducted matters as much as the result itself.
What the Numbers on the Report Mean
Two figures do the work on a paternity report. The first is the Combined Paternity Index, or CPI. It compares the likelihood that the tested man is the biological father against the likelihood that a random unrelated man is. When he is the father, the CPI runs extremely high, often above 100,000. When he is not, the CPI is zero.
The second figure is the probability of paternity, written as a percentage. At 99.99% or higher, the man “cannot be excluded” and is treated as the father. At 0%, he “is excluded.” Modern DNA testing does not produce middle results. You will not see 50% or 75%. The genetic markers either match closely enough for near-certainty or they don’t match at all.
The report lists the specific genetic locations, called loci, that the lab compared. Labs test at least 16 loci, and many test 20 or more. At each location, the child should share one marker with the mother and one with the father. Mismatches at three or more loci produce an exclusion.
At-Home Kits vs. Legal Tests
Not every DNA test can be used in court. At-home kits from pharmacies or online sellers can answer a personal question, but their results are inadmissible. Nobody verified who actually swabbed the cheeks that went into the envelope, so a court has no way to trust the identities behind the samples.
A legal DNA test is collected under supervision, usually at a clinic, hospital, or testing facility. A neutral collector checks each participant’s photo ID, photographs the participants, seals the samples in tamper-evident packaging, and documents every handoff from collection to lab to report. That documentation is the chain of custody, and it’s what makes the result admissible.
The lab itself has to be accredited for the results to carry weight. AABB, formerly the American Association of Blood Banks, is the primary accrediting body for relationship testing in the United States. Accreditation means the lab meets standards for sample handling, personnel qualifications, and quality control. 1AABB. About AABB Accreditation Results from an unaccredited lab are far more likely to be challenged or excluded.
The cost tracks the rigor. At-home kits typically run $100 to $200. A court-admissible test generally runs $350 to $500, including collection fees. Courts sometimes order one party to pay the full cost or split it between the parties.
Court-Ordered Testing
When paternity is disputed, either parent, or a state child support agency, can ask the court to order testing. Judges routinely grant those requests in child support and custody cases. The order will name the lab, set a deadline, and assign who pays.
Refusing the test is worse than taking it. A judge can hold the refusing party in contempt, which can bring fines or jail. More often, the court simply presumes paternity against whoever refused. A man who refuses can be declared the legal father and ordered to pay child support without any genetic evidence at all.
What a Positive Result Triggers for Child Support
Once paternity is confirmed, the biological father has a legal obligation to support the child. A child support order cannot be established against an unmarried father until paternity is established in the first place. 2Office of Child Support Enforcement. Establishing Fatherhood After that, the court applies state guidelines using both parents’ income and the child’s needs.
Results can also work the other direction. A man previously presumed to be the father, because he was married to the mother at the time of birth, for example, may take a test showing he is not the biological parent and petition to end his support obligation. Some states have formal procedures for disestablishing paternity in that situation. Others are reluctant to sever a parent-child bond that has already formed. The outcome depends on state law, how long the relationship has existed, and whether ending it serves the child’s best interests. 2Office of Child Support Enforcement. Establishing Fatherhood
What a Positive Result Triggers for Custody and Visitation
A confirmed DNA result does not by itself hand a father custody or visitation. It establishes biological parentage, which gives him legal standing to ask the court for those rights. Without established paternity, an unmarried father has no recognized claim to custody or visitation, so the test is a necessary first step rather than the last one.
Judges decide custody based on the child’s best interests. They look at each parent’s ability to provide stability, the child’s existing relationships, the parents’ mental and physical health, and the child’s own preferences if the child is old enough. Legal custody, covering major decisions about education, healthcare, and religion, can go to one parent or both jointly. Physical custody, which sets where the child lives, is decided separately.
Visitation typically goes to the parent without primary physical custody. Courts prefer arrangements that preserve a meaningful relationship with both parents, and many jurisdictions push parents toward a written parenting plan covering the schedule, holidays, and communication. If the parents cannot agree, a judge imposes a plan.
Benefits Beyond Support
Establishing paternity opens doors that go past monthly support checks. A child with a legally recognized father becomes eligible for that parent’s health insurance, life insurance proceeds, veterans’ benefits, and inheritance rights.
Social Security survivor benefits are one of the most significant. If a father dies, a child with established paternity can receive monthly survivor benefits based on his earnings record. Payments can continue until the child turns 18, or 19 if still in high school, and can total thousands of dollars over the child’s lifetime. The Social Security Administration applies the inheritance laws of the state where the father had a permanent home at the time of his death. The SSA will not enforce any state-law deadline requiring that a paternity action be started before the father’s death or within a specific window after it. 3Social Security Administration. Who Is the Insured’s Natural Child?
If the child is relying on a written acknowledgment of paternity or a court order requiring the father to support the child, those acts must have occurred before his death. 3Social Security Administration. Who Is the Insured’s Natural Child? That timing rule is one reason establishing paternity early matters, even when the parents’ relationship is stable and support is not in dispute.
Challenging the Results
DNA paternity tests are extremely accurate, but the results can still be challenged. The most common attacks target the process rather than the science. If the chain of custody was broken, if samples were stored improperly, or if the lab lacked current AABB accreditation, a court may discount or exclude the results. Lawyers scrutinize the paperwork for gaps: whether the collector was trained, whether samples were sealed in front of the participants, whether the lab’s accreditation was current at the time.
A party can also challenge the scientific reliability of the evidence. Under the Daubert standard, followed by federal courts and many state courts, the judge acts as a gatekeeper and evaluates whether expert testimony rests on a reliable foundation before it reaches the jury. 4Legal Information Institute. Daubert Standard DNA paternity testing is well-established enough that broad attacks on the science rarely succeed, but attacks on a specific lab’s execution can.
When a challenge succeeds, courts typically order a retest at a different accredited lab rather than throw the result out entirely. Both parties may have input on which lab. Deadlines to challenge vary widely by state. Some allow challenges until the child turns 18; others impose much shorter windows. Missing the window can foreclose any challenge, no matter what a later test might show.
When a Test Isn’t the Only Path
DNA testing is not the only way paternity gets established, and searchers looking at test results should know the alternatives so they don’t assume a test is required. When both parents agree on who the father is, they can sign a Voluntary Acknowledgment of Paternity, usually offered at the hospital right after birth or later through the state vital records office. Signed under penalty of perjury, it carries the same legal force as a court order. Either parent can rescind within 60 days; after that, overturning it requires proving fraud, duress, or a material mistake of fact in court. A man who signs and later suspects he is not the biological father can petition for testing, but courts weigh the established relationship heavily and may decline to undo paternity even with an exclusion result. 2Office of Child Support Enforcement. Establishing Fatherhood
Separately, most states run a putative father registry where an unmarried man can record his belief that he may have fathered a child. Registration does not establish paternity. It preserves the right to receive notice if someone tries to place the child for adoption. Deadlines are strict, often as short as 30 days after the birth. Without a timely registration, an adoption can proceed without the biological father ever hearing about it, and no later DNA test will undo it.