Twin Zygosity Test
This test is used to determine if a set of twins, are fraternal or identical, and can even determine if the
two children are in fact, siblings. The test is generally performed between two siblings. However, extra
options can be added, such as testing an additional sibling. Testing for Paternity and Maternity options
are also available.
What is the difference between identical and fraternal twins?
Identical twins come from one fertilized
egg and generally share a placenta, but fraternal twins come from two eggs fertilized by different
sperms. Of course, in some rare cases there are identical twins who do not share a placenta and
therefore it is sometimes difficult for the doctor to determine at birth whether the twins are identical or
What use is such a test?
Well, sometimes identical twins can share different appearances, or fraternal
twins can look quite similar so unless it has been predetermined it can be difficult to know for certain.
Usually the test is performed simply to fulfill personal curiosity, however there are health advantages as
well. In the event that one sibling needs an organ or tissue transplant, the test results may be useful in
determining whether one twin could be a donor for the other - generally identical twins are a perfect
match in these types of cases.