Paternity For Life
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Twin Zygosity Test

Identical twins (monozygotic twins) are conceived when a single sperm cell fertilises an ovum and the ovum splits, forming two zygotes with identical copies of DNA. Fraternal twins (heterozygotic twins) are conceived when two different ova are fertilised by two different sperm cells, resulting in two zygotes with different DNA profiles.

Quite often, parents can be misinformed during pregnancy and at birth regarding whether their twins are identical or fraternal. Ultrasounds may display one or two placentas during pregnancy. However, it is possible for identical twins to have separate placentas so this is not always a reliable indicator. Identical twins may not always have identical appearances, and non-identical twins can look very similar.

The only way to accurately confirm if twins are identical is through DNA testing. As identical twins are both from one egg, they will share the exact same DNA profile. Fraternal twins will not. A Twin Zygosity test will compare the DNA profile of the twins tested to confirm whether they are identical or not.

Why would I have a Twin Zygosity test?

Twin Zygosity testing can be completed out of curiosity, or for peace of mind purposes. However, it can also have important medical implications, including:

  • Identical twins will have the same blood group, and can donate blood to each other.
  • Identical twins may be able to donate organs to one another, with a much lower risk of rejection.
  • Assessing disease risk. If one twin has been diagnosed with a disease, knowing if the twins are identical can allow for early testing and diagnosis in the other twin.

Collecting Your DNA Sample

Upon receiving your application and payment, DNAQ will send a collection kit to your nominated address. This kit will contain everything you need to collect the samples, along with clear instructions on how to do so. We use mouth swabs for a quick and painless collection process. Once the samples have been collected, they are then returned to us in the supplied return envelope.


Results will be available within 5 working days from receipt of your samples at our laboratory. Results will only be sent to the parties being tested (or their legal guardian), to the email addresses provided at time of sample collection.

Please note that the results from Twin Zygosity testing are for peace of mind purposes only, and are not legally admissible.



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