What If You Find Out You're Not Your Child's Biological Father?

Establishing and contesting legal paternity in Wisconsin

By Katrina Styx | Reviewed by Canaan Suitt, J.D. | Last updated on May 2, 2023 Featuring practical insights from contributing attorney Aislinn M. Penkwitz

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Parenting a child can often be one of a father’s greatest joys. Unfortunately, it sometimes happens that a father may find out that he’s not his child’s biological parent, and that can lead to all sorts of questions for all parties involved.

While the emotional impact is difficult enough, there are potential legal implications to such a revelation. We spoke with Aislinn M. Penkwitz, a family law attorney at Nelson, Krueger & Millenbach in Milwaukee, about legal paternity and challenges to paternity.

Legal Paternity Explained

Legal paternity doesn’t have anything to do with the bond between a father and child; however, it does determine certain legal rights a father has in regards to that child. Those rights include child custody.

The parental rights that come with child custody include decision-making rights having to do with things like medical treatments, religious upbringing, and educational decisions, and decisions later in life like the child getting a driver’s license or enlisting in the military or getting married before the age of 18.

“Those are all decisions that a parent who is adjudicated a parent gets to make,” Penkwitz says. “And, generally, if we say it’s joint custody, that means that both parents have to agree or there’s no agreement to do it.”

Paternity rights also include placement, which has to do with where a child lives. Placement is also a factor in determining the amount of child support each party should pay.

In Wisconsin, it is possible for a biological father of a child to not be considered a child’s legal father. Determining legal paternity can be done a couple ways, Penkwitz says, “but all the processes require that the courts confer or give those rights to a dad.”

There are two methods a court uses to find if a person is a child’s legal father. First, if a father signs off on a child’s birth certificate, the court will generally assume that person is the child’s legal father. The other is to have the father in question take a paternity test, which would generally be done within the courthouse to ensure that the test results belong to the person appearing in court. “Usually they’re not looking at any other kind of testing that would be done outside of the court system,” Penkwitz says.

If there’s any question in a person’s mind that they may end up going to court with regard to these issues, they should reach out and talk to an attorney. If you don’t understand the conversation, that these terms have legal significance, you might be agreeing to things that you don’t intend to be agreeing to.

Aislinn M. Penkwitz

Challenging Legal Paternity

If a biological father is found to be someone other than a child’s legal father, any changes to legal paternity would have to be decided by court order. But any of the involved parties, whether the mother, adjudicated father or the biological father, can initiate the action.

An adjudicated father can’t abandon their rights, however. “The court’s not going to let there be a child without a parent,” Penkwitz notes. “So, one really quick way to know that the case isn’t going to be successful… is when you don’t have a replacement—you don’t have that bio dad. Maybe that person has passed away, maybe you can’t find them, maybe they’re not willing to cooperate.”

The court’s first priority is the child and determining what will be in the child’s best interest. To help determine the best interest of the child, the court may appoint a guardian ad litem. “They talk to both the parents, whether it’s the legal parent or not,” Penkwitz says. “They talk to the child. They talk to [any] therapists involved for the child or for the parents. They’ll talk to anybody that either parent would suggest that they talk to, in coming up with their recommendation.”

They’ll also consider the child’s education if they’re school-aged and anything that would affect the child’s well-being, as well as the feasibility of changing legal paternity.

When to Contact an Attorney

If you have any concerns about legal paternity or are facing potential legal action, it’s best to reach out to an experienced family law attorney, even if you decide not to hire one.

“If there’s any question in a person’s mind that they may end up going to court with regard to these issues, they should reach out and talk to an attorney,” Penkwitz says.

Having a conversation with a lawyer can help you understand the legal situation and what the courts can and cannot do. “If you don’t understand the conversation, that these terms have legal significance, you might be agreeing to things that you don’t intend to be agreeing to,” she says.

Another time to contact an attorney would be if one parent for some reason doesn’t want the child’s biological father of the child to be adjudicated.

“Maybe there’s some domestic violence issues, maybe there are some criminal concerns, maybe there are just thoughts that, ‘Hey, I don’t want this to happen, is this a good enough reason not to let it happen?’” In those cases, an attorney can determine if the reason meets the court’s standards and help families find legal solutions.

It’s worth noting that state laws can and do change. Penkwitz says that recent changes to the statute may change the role child support agencies will play in adjudicating paternity rights.

“People have to be paying attention to what [documents] they’re getting,” she says, “making sure that if they see something, if they’re not sure what they’re reading or what they’re being asked to do, call an attorney. Many attorneys give free consultations, and they can help at least address what the procedure is going forward. Attorneys can’t give necessarily legal advice in the consult, but they can certainly address the fact that there’s a certain procedure coming, and why it’s important to participate in it in a certain way.”

For more information about this area of law, read our overview articles on family law, custody and visitation, and father’s rights.

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