What Is Genetic Testing for Paternity?

Genetic testing for paternity is the DNA analysis courts use to determine whether a particular person is a child's biological parent. In Washington, it is not a casual home kit but a carefully regulated process, and the law spells out when it can be ordered, how it must be performed, and how much certainty it takes to prove parentage. This topic is part of Washington paternity law. If a result does not resolve parentage, review the options for additional testing and a timely database objection.

When a Court Can Order Genetic Testing

Genetic testing in a parentage case usually starts with a court order rather than a private decision. Under RCW 26.26A.310, in a proceeding to determine parentage, the court must order the child and any other individual to submit to genetic testing when a party supports the request with a sworn statement. That statement has to either allege a reasonable possibility that the individual is the child's genetic parent or deny genetic parentage while stating facts that show a reasonable possibility the individual is not the parent. The sworn-statement requirement keeps testing from being demanded on a whim. Related guides cover How Do I Get Court-Ordered Paternity Testing? and What Is a Paternity Test and How Does It Work?.

The same statute sets some sensible limits. The court cannot order testing of a fetus before birth. Testing of the woman who gave birth is not required as a precondition to testing the child and the alleged parent, so the analysis can move forward even if she is unavailable. And the law recognizes that testing is not always appropriate. In cases involving a presumed parent, a claimed de facto parent under RCW 26.26A.440, or a challenge to an acknowledgment of parentage, the court may actually deny a testing request after weighing certain factors, because sometimes disrupting a settled parental relationship is not in the child's interest. An order to test is enforceable through the court's contempt power.

How the Testing Must Be Done

Not just any DNA test will satisfy a Washington court. RCW 26.26A.315 requires that genetic testing be of a type reasonably relied on by experts in the field and that it be performed in a laboratory accredited by the AABB, formerly the American Association of Blood Banks, or by another accrediting body approved by the United States Department of Health and Human Services. This accreditation requirement is what separates court-admissible testing from an over-the-counter kit.

The testing itself is not invasive. The statute allows a specimen to consist of blood, buccal cells, which are the cells collected with a cheek swab, bone, hair, or other body tissue or fluid, and the samples do not all have to be the same kind for each person tested. In practice, most paternity testing today uses a simple cheek swab.

How Reliable the Result Has to Be

Washington does not treat a mere probability as proof. RCW 26.26A.325 establishes a demanding standard. A person is identified as a genetic parent only when the testing shows at least a ninety-nine percent probability of parentage, using a prior probability of 0.50, along with a combined relationship index of at least one hundred to one. That is a high bar by design, meant to ensure that a genetic finding of parentage rests on solid science.

To keep the statistics fair, RCW 26.26A.315 lets a party object to the ethnic or racial database the laboratory used to calculate the result and request a recalculation within thirty days of the report. The frequencies drawn from those databases can affect the final numbers, so the law provides a way to check them.

Trusting the Report

For a genetic test to carry weight in court, the paperwork behind it has to be trustworthy. Under RCW 26.26A.320, a report of genetic testing must be in a record and signed under penalty of perjury by a designee of the laboratory, and a report that meets the statute's requirements is self-authenticating. The statute also lists the documentation needed to establish a reliable chain of custody, including the name and photograph of each person tested, who collected each sample, where and when it was collected, and who received it at the lab. When that documentation is in order, the results can come into evidence without live testimony from the lab, which saves time and expense.

Who Pays

Cost is a common concern, and the law addresses it directly. RCW 26.26A.330 provides that the cost of initial genetic testing must be paid in advance, whether by a child support agency handling the case, by the person who requested the testing, as the parties agree, or as the court orders. If a child support agency pays, it can later seek reimbursement from the parent whose relationship to the child is established.

Why It Matters for Snohomish County Families

For families in Everett, Marysville, and throughout Snohomish County, a reliable parentage determination is the foundation for child support obligations, parenting plans, medical history, and a child's inheritance rights. Because so much rides on the outcome, Washington built a process that prizes accuracy and admissibility over convenience.

Every case is different, and this article speaks in general terms rather than about any particular situation. If you have questions about genetic testing in a parentage matter, the Law Office of Chad Foster can help you understand how the process works and what it means for your family. Reach out to learn more.