You Can't Escape Child Support? - DNA Paternity Testing and Acknowledgment of a Child -

Rewritten on: September 13, 2024

This article explains in detail the relationship between DNA paternity testing and the acknowledgment of a child, including the obligation to pay child support, the procedure for denial of legitimacy, and the importance of legal DNA testing. Conducting a DNA test before acknowledgment can help you avoid unnecessary trouble.

DNA Paternity Testing and Acknowledgment of a Child ― The Reality of Not Being Able to Escape Child Support, and the Right Way to Respond

When a woman tells you, "This is your child, acknowledge it," and you're not sure whether the child is really yours, what should you do? Do you assume that acknowledging the child on the spur of the moment is fine? You may feel you bear some responsibility, or that she seems to be struggling, so you go along with it out of a sense of obligation — there can be many reasons behind such a decision.

However, acknowledgment is an act that, once made, produces an extremely significant legal effect. If you agree to it too easily, it can be extremely difficult to retract later, and you may end up bearing the legal duties of a father for the rest of your life even if the child turns out not to be biologically yours. That is exactly why it is so important to conduct a DNA paternity test and scientifically confirm whether a biological parent-child relationship exists before agreeing to acknowledgment.

■ What Exactly Is "Acknowledgment"? ― The Establishment of a Legal Father-Child Relationship

Acknowledgment (ninchi) is the act by which, when a child is born to an unmarried man and woman, the man recognized as the father accepts the child as his own and thereby establishes a legal father-child relationship [ref:1]. In the case of a child born to a married couple, Article 772 of the Civil Code's "presumption of legitimacy" automatically presumes the child to be the husband's; but for unmarried couples, while the relationship with the mother is automatically established by the fact of childbirth, the legal relationship with the father is not established without acknowledgment.

Acknowledgment broadly falls into two types: "voluntary acknowledgment" and "compulsory acknowledgment (acknowledgment by court judgment)." Voluntary acknowledgment is carried out when the father submits a notification of acknowledgment to the municipal government office on his own initiative. Compulsory acknowledgment, on the other hand, is the procedure by which, if the father does not voluntarily acknowledge the child, the child or their legal representative (such as the mother) files a paternity suit in family court, and the father-child relationship is determined through a court judgment [ref:2].

Acknowledgment brings about the following significant legal effects.

• An obligation to pay monthly child support arises
• If the father dies, the child gains inheritance rights
• The fact of acknowledgment is recorded in the family register
• The child's surname can be changed to the father's surname
• The matter becomes subject to discussion regarding parental custody

One point that deserves particular attention is that acknowledgment is established, and recorded as such in the family register, even if the acknowledged child is not actually the (biological) child of the person acknowledging them. In other words, once acknowledgment has been made, a legal parent-child relationship is established regardless of whether a biological blood relationship actually exists, meaning the father will bear this legal duty for the rest of his life.

■ Paying Child Support ― An Unavoidable Legal Obligation

No matter how much you, as the legal father, may not want to pay child support, there is no escaping it. Child support is an indispensable expense for a child's healthy upbringing, and it is clearly stipulated in the Civil Code as a parental obligation. Even if you refuse to acknowledge the child, the woman can still file for mediation seeking acknowledgment.

Even if a man refuses a DNA test to the very end, if the family court finds that a father-child relationship is plausible, compulsory acknowledgment can still be ordered [ref:3]. This is because refusing a DNA test can itself be interpreted unfavorably by the court as evidence of "circumstances suggesting a reluctance to admit the father-child relationship." Even if you intentionally let child support payments lapse, the amount can be collected by compulsory execution against your wages or bank deposits.

The amount of child support is generally determined based on the "Child Support Calculation Table" published by the courts. It is calculated by taking into account the respective annual incomes of the father and mother, as well as the age and number of children, and typically comes out to roughly 20,000 to 100,000 yen per month per child. This payment continues, in principle, until the child reaches adulthood (and in some cases, until graduation from university).

On the other hand, if a DNA test rules out a biological blood relationship, then naturally there is no longer any obligation regarding child support or inheritance division. Rather than simply refusing a DNA test, it is necessary to actively undergo DNA testing yourself and investigate the actual blood relationship. Proactively undergoing testing is the most rational means of protecting your own rights.

■ Basic Knowledge of How Child Support Is Calculated and Paid

Many people have questions about the specific amount and method of paying child support. Below is an overview of the basic process regarding child support.

1. Legal establishment of the father-child relationship (submission of an acknowledgment notification, or compulsory acknowledgment through a court judgment)
2. Discussion between the parties regarding the amount of child support (if no agreement is reached, mediation at family court)
3. Determination of the amount based on the child support calculation table
4. Preparation of a notarized document or finalization of the mediation record
5. Start of regular monthly payments (bank transfer is common)

Because an agreement on child support made only verbally carries weak legal force, it is important to have a notarized document prepared. If a "clause consenting to compulsory execution" is included in the notarized document, compulsory execution becomes possible without going through a lawsuit if payments lapse. In other words, it is practically almost impossible to escape the obligation to pay child support.

■ If You Have Already Acknowledged the Child ― The Procedure and Deadline for Denial of Legitimacy

Denial of legitimacy refers to denying the father-child relationship in cases where legitimacy is presumed (a child born during marriage, or within 300 days after divorce), on the grounds that the child is not actually one's own [ref:4]. This system is a legal procedure for overturning the automatic presumption of a father-child relationship created by the Civil Code's presumption-of-legitimacy system.

There is a strict deadline for filing a denial of legitimacy. Before the 2022 Civil Code amendment (which took effect on April 1, 2024), the father had to file within one year of learning of the child's birth. After the amendment, this period was extended to within three years, but even so, once the deadline passes, the father-child relationship becomes legally fixed [ref:5].

If a long period passes after a DNA test rules out a blood relationship, it may become impossible to file a denial of legitimacy, and the father-child relationship will become fixed. You may then be forced to raise a child who might not be yours, and obligations of support as well as inheritance rights will also arise. If you have even the slightest doubt, you need to prepare immediately.

Also, in cases not covered by denial of legitimacy (such as voluntary acknowledgment where there is no marital relationship), a separate legal procedure called an "action to invalidate acknowledgment" is required. An action to invalidate acknowledgment is a procedure for negating the effect of acknowledgment when the acknowledgment does not reflect the truth (i.e., no biological parent-child relationship exists). In this case as well, the results of DNA testing serve as decisive evidence.

■ If You're Unsure Whether to Deny Legitimacy, Confirm the Father-Child Relationship With DNA Testing

One thing to be careful of here: if you simply keep avoiding discussion without doing anything, acknowledgment can end up being compelled even without a DNA test. In other words, it is entirely possible to end up having acknowledged a child who is not actually yours. Even if a party refuses a DNA test, family courts may still recognize acknowledgment by comprehensively weighing other evidence (such as the length of the relationship, the fact of sexual relations, and the child's physical resemblance).

You are only obligated to acknowledge a child if it is truly your own. Unless you are absolutely certain the child is yours, you should undergo DNA testing. If DNA testing shows there is no blood relationship, this becomes the strongest possible evidence for refusing to acknowledge the child.

Modern DNA testing technology is extremely precise, and a method called STR (Short Tandem Repeat) analysis can determine the probability of a parent-child relationship with an accuracy of 99.99% or higher [ref:6]. Sample collection needed for testing is as simple as swabbing the inside of your cheek and your child's cheek ten times back and forth vertically and horizontally, and testing is also possible using a toothbrush, hair, or even an umbilical cord stump more than 25 years old. A sample from the mother is not required to test the father-child relationship.

In case of any misunderstanding, it is advisable to first confirm matters privately in advance. Since courts and hospitals cannot perform DNA testing themselves, you will need to request testing from a company that specializes in DNA testing on your own.

■ Types of DNA Testing ― The Difference Between Private and Legal Testing

DNA testing broadly falls into two categories: "private testing" and "legal testing." It is important to understand the characteristics of each and choose the testing method suited to your situation.

We recommend first confirming whether a blood relationship exists through private testing, and then, if legal procedures turn out to be necessary based on those results, requesting a separate legal test as the next step.

■ Legal DNA Testing for Court Proceedings or Mediation

If you are going to submit a denial of legitimacy to the court, you need legal testing, in which sample collection is carried out with a third party present. This is because, if the requester collects samples from all participants themselves and submits them to the testing organization, there is a risk that someone else's sample could be submitted in place of the father's. This might not be intentional fraud but simply a mistake — either way, legal DNA testing, in which sample collection is conducted under the supervision of specialized staff, is necessary to confirm accurate results.

Legal DNA testing requires the following strict procedures.

• Identity verification using identification documents (such as a driver's license or passport)
• Presence of specialized staff during sample collection
• Strict management and storage of collected samples (ensuring chain of custody)
• Signature and seal of the witnessing party on the testing result report
• Sealing procedures to prevent tampering

Any DNA test submitted to immigration authorities or courts is, by definition, a legal DNA test. Since acknowledgment is an event that can greatly affect a person's life, you should choose a reliable company. When selecting a testing organization, it is important to confirm whether it meets international quality standards, such as ISO 17025 accreditation or AABB (American Association of Blood Banks) accreditation [ref:7].

■ The Risk of Leaving the Acknowledgment Issue Unresolved ― The Importance of Acting Early

Putting off the issue of acknowledgment carries many risks. As mentioned above, there is a deadline for filing a denial of legitimacy, and if the other party files for mediation or litigation seeking acknowledgment, the longer your response is delayed, the more you may be forced into a disadvantageous position.

This kind of anxiety is hard to discuss with others, and time is limited. It might just be needless worry. Rather than agonizing over it, we believe you should first clarify the truth with scientific evidence, and then decide how to act. DNA testing puts an end to emotional back-and-forth and serves as the first step toward a resolution based on objective fact.

At seeDNA Genetic Medical Institute, we provide accurate and prompt DNA paternity testing backed by extensive experience and advanced technical capability. We are thorough in our attention to privacy, so please feel free to consult with us even about sensitive matters.

Frequently Asked Questions

Q1. What happens if I keep refusing to acknowledge the child?

A. The woman can file for mediation or litigation seeking acknowledgment at family court. Even if you keep refusing a DNA test, if the court determines the father-child relationship based on other evidence, compulsory acknowledgment may be ordered. In fact, refusing a DNA test can work against you, so we recommend proactively undergoing testing and responding based on scientific evidence.

Q2. How accurate is DNA testing?

A. Modern DNA testing using STR analysis can prove a parent-child relationship with an accuracy of 99.99% or higher when such a relationship exists, and can rule it out with 100% certainty when it does not exist. Testing organizations that comply with international quality standards offer an extremely high degree of reliability [ref:6].

Q3. What is the deadline for filing a denial of legitimacy?

A. Under the amended Civil Code, which took effect on April 1, 2024, the father must file within three years of learning of the child's birth (previously, it was within one year). Because a denial of legitimacy claim may no longer be accepted once this deadline passes — even if a DNA test later reveals there is no blood relationship — it is important to act early [ref:5].

Q4. What is the difference between private testing and legal testing?

A. Private testing is a method in which the requester collects samples at home and mails them in; it is suitable for personal confirmation. Legal testing involves sample collection witnessed by a third-party specialized staff member, along with identity verification, making it admissible as evidence in court. If you are planning to pursue a denial of legitimacy or paternity litigation, be sure to choose legal testing.

Q5. Is a sample from the mother required for DNA testing?

A. To confirm a father-child relationship, testing can be performed using only samples from the father and child. A sample from the mother is not required. However, submitting the mother's sample as well can, in some cases, allow for even greater testing accuracy. Besides the mucous membrane on the inside of the cheek (oral swab), special samples such as a toothbrush or hair can also be used for testing.

Q6. If it turns out there is no blood relationship after acknowledgment, can the acknowledgment be revoked?

A. If the acknowledgment does not reflect the truth (that is, no biological parent-child relationship exists), it is possible to negate the effect of the acknowledgment through an "action to invalidate acknowledgment." However, this procedure requires filing with the family court, and the results of DNA testing serve as decisive evidence. If the invalidation of acknowledgment is recognized, the obligation to pay child support and inheritance rights are retroactively extinguished.

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