Are They Identical or Fraternal?
Knowing whether twins are identical or fraternal is often difficult. Appearance alone often is not a reliable method for determining twin zygosity because identical twins do not always look exactly the same, and fraternal twins can sometimes look very similar, leading to confusion about exactly what type of twins they are. Sometimes, twins grow up never knowing for sure whether they are identical or fraternal.
Determining Twin Zygosity at Birth
At the time of birth, the physician will try to get an idea of whether twins are identical or fraternal by examining whether they share the same sac. Identical twins often form in a single sac, sharing a placenta and amniotic membranes. Fraternal twins often form in two separate sacs. However, up to 25% of the time, this method of determining twin type is not accurate and can be very misleading. In some cases, twins can have two sets of outer sacs (dichorionic) and still be identical twins. Also, the two placentas of fraternal twins can sometimes fuse together and appear to be one.
Conclusive Determination of Twin Zygosity Using DNA
The only way to conclusively determine whether twins of the same sex are identical is through a simple DNA test. For this reason, many parents of twins will consider a private DNA test for twins to determine conclusively whether the twins are identical or fraternal. The DNA twin test is fast, simple and painless. A DNA sample is taken from each child by rubbing a painless swab gently inside the child's mouth for ten seconds. The samples are then submitted to the laboratory for testing and conclusive results are available within 3 to 5 business days.
- Check the status of your test online and download your test report instantly when it is ready
- Results in 3 to 5 business days
What if the individuals to be tested live at different addresses, can you split the kit?
Yes, if the individuals to be tested live in different cities, or even different countries, we can split the kit and send each component to a different address. Since the kits are individually barcoded, the samples will still be tested together even if the are sent back separately. To order a split kit, please write the following into the comments box of the online order form "Please split kit". Please also indicate the name and address to send each component.