When is DNA Paternity Testing Needed to Prove Parentage?

 Posted on July 27, 2026 in Paternity

Families in Illinois are diverse, and many different arrangements allow parents to raise their children with love and strength. Although many women have no choice but to be single parents, research consistently suggests that children are more likely to succeed by every measurable outcome when they have a father who is emotionally present and financially involved in ensuring his child has what he or she needs.

Unfortunately, fathers are not always eager to take financial or emotional responsibility for their children and may be unwilling to voluntarily acknowledge paternity. When this happens, or when there is a question as to whether a man is indeed the biological father of a child, Illinois courts can take measures like DNA paternity testing to ensure that a man is held responsible for the fathering of a child and for contributing to that child's financial needs.

As one of the largest and most prestigious firms in DuPage County, our Wheaton, IL paternity attorneys at The Stogsdill Law Firm, P.C. have the resources to represent you in a disputed parentage case.

How Do DNA Tests Work in Paternity Cases?

The most common DNA paternity tests take a simple cheek swab from the child and the alleged father, and send these samples to a laboratory for comparison. The lab will compare a particular part of the child's DNA to the father’s DNA and can estimate parentage with almost 100 percent accuracy.

If either parent has questions or doubts about the reliability of a DNA test, he or she can submit samples to an independent laboratory as long as the laboratory meets state requirements. Usually, the parent requesting the test is responsible for paying, though the court can also split the cost between the parties upon request.

When Does a Court Order DNA Testing in 2026?

When parents are unmarried and do not sign a Voluntary Acknowledgement of Parentage (VAP) form, they must take an alternative route to establish paternity. Either parent may not want to sign the VAP for a number of reasons, including when one parent contests the alleged paternity of the child. In cases like this, DNA testing is a safe, painless, reliable method of determining paternity.

Illinois courts can order a man to submit to a paternity test and have the authority to enact sanctions if he does not comply. Avoiding a court-ordered paternity test will not allow a father to avoid responsibility for a child and could result in serious consequences.

Establishing paternity has the potential to benefit everyone involved. Once a DNA test establishes paternity, a man can be ordered to pay child support. He can also pursue parental rights, like parenting time and parental responsibilities. The father benefits from having a legal relationship with his child, the mother benefits from the ability to get help raising the child, and the child benefits from having both of his or her parents participate in his or her upbringing.

What Happens if the Father Refuses a DNA Test in Illinois?

A court can order both a mother and an alleged father to take a DNA test in a paternity case. If a man refuses to comply with a court-ordered test, he cannot simply avoid the case. Under Illinois law, a court may issue a default judgment against the party who doesn’t appear in court after being served.

A judge may also use other tools to enforce DNA testing, such as holding the man in contempt of court (750 ILCS 46/615). Contempt can lead to fines or other penalties.

What if a Mother Denies That a Father Is Related to the Child?

Sometimes a man believes he is the biological father of a child, but the mother disagrees or will not confirm it. In these cases, a man can file a petition with the court to establish parentage. He does not need the mother's agreement to start this process.

Once the case is filed, either party can ask the court to order genetic testing. With a few exceptions, the court will then direct the mother, the child, and the man to take the test. If the results show a high probability of parentage, the court can issue a legal finding of paternity. A mother cannot block a court order for testing just because she disagrees with the outcome.

What Happens if a DNA Test Confirms a Man Is Not the Biological Parent in Illinois?

If a DNA test shows a man is not the biological father, the court will usually dismiss the paternity case against him. The situation becomes more complicated if a man was already named the legal father before the test, such as through a signed VAP. Going forward, the court may release the non-biological father from child support responsibilities. However, the child’s best interests come first, and in some situations where the father was present for a long time, he may still be ordered to pay child support.

In that case, disproving biological parentage later does not always erase his legal status right away. He may need to file a separate petition asking the court to cancel, or disestablish, his legal parentage. Courts consider how much time has passed and whether the man acted quickly once he learned the truth. Waiting too long can make it harder to undo an existing support order or custody arrangement.

If a man later discovers he is not the father when he is presumed to be the parent, he then has two years to challenge it in court. Specifically, the two-year window goes into effect once a man knows or should have known "the relevant facts" that cause him to doubt the parent-child relationship.

On the other hand, if a man signs a VAP, he has two years from the date it becomes effective to challenge it. Courts allow challenges based on fraud, duress, or a genuine mistake of fact, but proving one of these becomes harder as time passes.

Contact a Wheaton, IL Family Law Attorney

If you are struggling to establish parentage, you may want to get help from the experienced team of DuPage County, IL paternity lawyers with The Stogsdill Law Firm, P.C.. We have the experience and legal knowledge necessary to help you explore your options and choose a path that makes sense for you and your family. Call us today at 630-462-9500 to schedule a confidential case review and learn more about how we may be able to help.