Paternity For Life

Twin Zygosity DNA 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.

Identical twins may not always have identical appearances, and non-identical twins can look very similar. Therefore, appearance is not always an accurate indicator that twins are identical. Identical twins can also have separate placentas, so the number of placentas is also not always an accurate indicator. The only way to accurately confirm if twins are identical or not is through DNA testing.

As identical twins are both from one egg, they will share the exact same DNA profile, whereas fraternal twins will not. A Twin Zygosity DNA test will compare the DNA profile of the twins tested to confirm whether they are identical or not.

Reasons for Twin Zygosity DNA Testing

Twin Zygosity DNA Testing can be completed out of curiosity or for peace of mind purposes, to confirm if twins are identical or fraternal. For some twins, this can help to improve their sense of self and identity, or help to build their relationship their twin.

Testing can also be completed for a number of medical reasons, including:

  • Identical twins will have the same blood group, and therefore can donate blood to each other.
  • Identical twins can donate organs to each other with a very low risk of rejection of the organ.
  • 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

Samples can be collected by the individuals to be tested themselves, at home. Paternity for Life uses mouth swabs for a simple and painless collection process. Upon receiving your application and payment, Paternity for Life 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. 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 when we receive 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. A hard copy of your results can also be arranged (additional fees apply).



Paternity DNA Testing Lab

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