Zygosity Testing

What relationship does Zygosity Testing Prove?

Zygosity testing can be used to determine whether multiple children from the same birth, i.e. twins, triplets etc. are genetically identical or not.

Identical siblings are known as monozygotic. This means that they were formed from a single fertilised egg, which went on to split into separate embryos and that their DNA is exactly the same.

Non-identical siblings are known as dizygotic. This means that they are the result of separate fertilised eggs and that they share half of their genes in common like other siblings.

Why would you undertake a Zygosity Test?

There are various reasons why individuals may wish to gain an understanding of their own, or their children’s zygosity status. These may include the following:

  • Their own interest
  • To avoid embarrassment when asked the common question “Are they identical?”
  • To reinforce the need to treat the siblings as individuals
  • To assess the likelihood of conceiving twins again
  • To participate in any research about multiple births

Who needs to be tested?

  • Twins
  • Triplets
  • Quadruplets etc.

How reliable are the Results?

The results of this test are more than 99.99% conclusive.


Book This Test

Can I obtain support after the test?

Yes, NorthGene work with the Multiple Birth Foundation who supports families which have children from multiple births, or individuals from a multiple birth. They can be contacted using the following information:

The Multiple Births Foundation

Hammersmith House Level 4,
Queen Charlotte’s & Chelsea Hospital,
Du Cane Road,
W12 0HS

T: 020 3313 3519 / 020 8313 3519

W: www.multiplebirths.org.uk

E: mbf@imperial.nhs.uk

Other Relationship Testing

If you would like to discuss the possibility of performing other relationship tests please contact our Client Liaison Team on 0870 803 0999.