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Can Paternity Tests Get It Wrong?

David Scott, P.A. Aug. 21, 2022

Since Florida laws require fathers to financially provide for their children’s shelter and upbringing, determining paternity is a high priority, and paternity tests are sometimes ordered by the courts.

Can paternity tests be wrong, though? Read on to learn about how paternity tests work, how accurate they really are, and why your tests results might just be incorrect.

How Paternity Tests Work

Paternity tests use DNA to decide who a child’s father is. Each child gets 50 percent of their DNA from their mother and 50 percent from their father. Since every cell in a person’s body contains DNA, samples can be collected in several different ways. Sources for DNA include:

  • Blood

  • Saliva

  • Hair

  • Swab from cheek

  • Umbilical cord

  • Semen

  • Any other human tissue

Only identical twins share exact DNA strands. Family members, such as siblings or cousins, share DNA in varying amounts.

A paternity test requires DNA samples from both the child and the potential father. If the father’s DNA is not available, the alleged grandparents or other relatives can provide DNA samples for testing.

The acceptable rate for most paternity tests is over 90 percent. If the DNA samples match from the child, mother, and father, the likelihood of accuracy is 99.9 percent.

Cheek swabs and blood tests can have the same accuracy, and non-invasive collection can be just as accurate as invasive collection.

Invasive vs. Noninvasive DNA Collection

DNA can be collected while the child is still in the womb or any time after the child is born. While the child is in the womb, two collection methods may be used. The first method is amniocentesis, which uses the amniotic fluid from the mother’s womb to collect floating cells that contain the child’s DNA. The second method is chorionic villi sampling, which collects DNA cells from the uterine walls.

Both tests can pose risks to the health of the baby and the mother. They can also be expensive and not covered by insurance. However, these test results are highly accurate.

A non-invasive test uses the mother’s blood to collect the child’s DNA. The blood test can be conducted as soon as the eighth week of pregnancy. The father can provide a cheek swab or blood sample for the test. A non-invasive test is less expensive and (as mentioned above) can be just as accurate as an invasive test.

After the child is born, cheek swabs can be taken from the mother, father, and baby. At-home tests usually provide accurate results, though the court only accepts professional tests as evidence.

Inclusion vs. Exclusion

Two types of tests measure DNA testing results. They both look at the number of DNA loci harvested from the test donors.

An inclusion test indicates the likelihood of the man to be the father of the child. The more loci that match, the higher the likelihood that the man is the child’s father.

An exclusion test negates any chromosomes from the man that do not match those of the baby. Since 50 percent of the baby’s chromosomes must be provided by its father, the exclusion test rules out anyone who is not the baby’s father.

The exclusion test has a higher rate of accuracy than the inclusion test.

Ways a Paternity Test May Be Wrong

Despite the high rate of accuracy for paternity tests in general, that does not mean that tests are always right. Beyond the relatively small percentage of tests that are just inaccurate, one of the biggest reasons for “wrong” results is simple: error.

Though errors in paternity tests are relatively uncommon, they do occur. A test may be wrong for the following reasons:

Tampering may occur. If anyone wishes to skew the test results and somehow gains access to the test sample, the results can be false.

Lab error. This can produce either false positive or false negative results.

Relatives may test as potential fathers. For example, the father’s brother may test positive for paternity even if no relationship exists between him and the child’s mother.

DNA mutations Though these are exceedingly rare, they can produce false results.

What to Do If You Need Assistance

The first step in challenging paternity is to file a court complaint. Paternity issues can be emotionally challenging for everyone involved. It’s crucial to involve the help of an experienced family law attorney when you are navigating these issues.

Whether you wish to prove paternity or fight paternity test results, a skilled attorney will provide an initial consultation to confidentially discuss your case details and detail the options that are available to you.