Paternity testing

Paternity testing is a medical test used to help confirm if a person is the biological parent of a child. The term can feel gendered, and some people prefer the more inclusive term ‘parentage testing’, which recognises different family structures and identities. In this article, we use the more widely recognised term ‘paternity testing’, but acknowledge that ‘parentage testing’ may be preferred by some people.

The test works by comparing genetic material (DNA) from the child and the person who may be the biological father. Since children inherit half their DNA from each biological parent, the test can show if there is a match.

Paternity (or ‘parentage’) testing can be done during pregnancy or after a baby is born.

During pregnancy, testing is usually done using a blood sample from the pregnant person — this blood has small amounts of the baby’s DNA.

After birth, testing is usually done using:

• mouth (cheek) swab (most common)
• blood sample by finger prick
• a blood sample taken from a vein

People may choose to do a paternity test for personal, medical or legal reasons.
Some common reasons include:

• to check if a person is the biological parent of a child
• legal matters, such as child support or custody arrangements
• immigration
• access to family medical history to help guide healthcare decisions
• inheritance cases
• personal reassurance

For some families, the decision can feel urgent. For others, it may take time to think through. It’s a good idea to ask questions and seek advice before deciding to get a paternity test.

Different people may request a paternity test, depending on the situation. This may include:

• the child’s mother or birth parent
• the person who may be the biological parent
• a legal guardian
• a mature-aged child (aged 18 years or older)
• a court

In Australia, courts can order paternity testing in some situations, especially when it relates to child support or parenting arrangements.

You usually need to get consent before a paternity test can be carried out. For adults, each person being tested must give their consent. For a child, a parent or legal guardian usually gives consent on the child’s behalf.

If someone does not agree to testing, it usually cannot go ahead unless a court orders it.

It’s important to know that taking a DNA sample without someone’s knowledge or permission may not be legal and could affect whether results are accepted in court.

If the test is not being done for legal purposes, the rules can vary. Some home testing kits do not have strict processes to confirm consent. This can increase the risk of samples being collected without consent or used incorrectly.

If you’re unsure, it can help to speak with your doctor or legal adviser. They can explain your rights and what the process involves, so you can make an informed choice.

Most paternity tests are simple and will not hurt.

After birth, testing usually involves:

• gently swabbing the inside of your mouth to collect DNA
• sending the sample to an accredited laboratory for analysis

During pregnancy, some tests can be done using a:

• blood sample from the pregnant person
• DNA sample from the potential parent

These are known as non-invasive prenatal paternity tests and carry no risk to the pregnancy.

Home paternity testing

Home testing uses kits that you can use wherever you are comfortable. You collect the sample yourself and then send the samples to a laboratory (lab) by mail. They are available from some laboratories, online or from some pharmacies.

Results from home tests are not legally recognised as they may not follow strict identification or consent procedures.

If you need results for legal purposes, you must use a National Association of Testing Authorities (NATA) accredited testing service that follows proper procedures.

If you’re unsure, speak with your doctor or legal adviser before deciding what type of testing is best for your situation.

Paternity tests are highly accurate when done correctly.

A calculation called a paternity index shows how likely it is that the tested person is the biological parent, compared with a random person from the general population. This result is then used to give an overall probability that the person is the parent.

Errors are rare, but can happen if samples are contaminated or mislabelled. This is why legal tests have strict processes.

The cost of paternity testing can vary depending on the type of test and how many people are being tested.

In Australia, costs start around $500 to test one child and one parent. In many cases, you won’t need to provide the DNA of the child’s other biological parent (for example, their mother), but it may help improve the accuracy of the results. Some providers include this at no extra cost. 

Non-invasive prenatal paternity tests are usually more expensive. You can speak to your doctor for more information or advice.

Non-legal testing or home testing kits can cost a few hundred dollars.

Deciding whether to have a paternity test can feel overwhelming. Research shows that paternity testing can affect many parts of family life — including relationships, identity and legal responsibilities (including child support and parenting arrangements).

Before going ahead, it can help to take some time to think about:

• how the results might affect you, your child and your family
• if you need legal advice, especially if the test relates to child support or court matters
• how you will share or manage the results

You don’t have to make this decision on your own. It can be helpful to:

• speak with your doctor, midwife or counsellor
• seek legal advice, if needed
• talk to a trusted support person 

Taking the time to understand your options and get the right support can help you make a decision that feels right for you and your family.

You don’t have to navigate this alone. Resources and support are available:

• The NSW Government has further information on paternity testing, costs and what to expect.
• Find a NATA-accredited laboratory.
• The Australian Government has a list of laboratories and nominated reporters for parentage (paternity) testing.
• Healthy Male provides useful websites and support.

Information for Aboriginal and/or Torres Strait Islander peoples

Australian Alliance for Indigenous Genomics (ALIGN) has further information about DNA, DNA testing risks, and how to find a genetic counsellor.