ARE YOUR TWINS IDENTICAL OR FRATERNAL?
Terms
Monozygotic – identical Dizygotic – fraternal
How do you know if your twins are identical or fraternal?
It is easy if they are different sexes – boys and girls are not identical!
If they are the same sex, use this diagram to determine the zygosity of your twins (or triplets).
If you get to this point, the only certain way to know the zygosity is to have a zygosity test done. It is a very simple procedure. A cheek swab is taken from each child and sent to a laboratory where they examine the DNA to see how closely it matches.
For more information on zygosity, visit the Twins Research Australia website
Diagram from TRA, Conversations in Twin Research – The importance of zygosity knowledge for twins
and science
Written 2021
M. Rankin, Chairperson ICOMBO www.icombo.org Used with Permission of ICOMBO (May 2021)