Twin Zygosity Testing
Identical twins often show different physical characteristicssometimes they can be different enough to be mistaken for fraternal twins. In the same way, some fraternal twins of the same sex may look very similar and might be mistaken for identical twins.
At birth, a physician usually is able to tell the difference by looking at whether the twins share a placenta (identical) or are in two different placentas (fraternal). There are instances, however, when identical twins have separate placentas and when fraternal twins appear to share one placenta.
Identical vs. Fraternal Twins
Identical twins come from one fertilized egg, called a zygote. The zygote, which usually develops into one child, grows and splits early in development to form two embryosidentical twins. Because the twins come from one egg and one sperm, they have exactly the same DNA.
Fraternal twins, on the other hand, develop when there are two different eggs in the mother’s womb that are fertilized by two different sperms. Fraternal twins will not have exactly the same DNA, although like other siblings, they can be expected to share some of the DNA they inherit from both parents.
Uses of the Twin Zygosity Test
A twin zygosity test reveals with certainty whether twins are identical or fraternal. The results of the test are mainly used to satisfy personal curiosity, but there are health advantages as well. In the event that one sibling needs an organ or tissue transplant, the test results may be used as a guide in determining whether his/her twin could be a donoridentical twins are a perfect match in such cases.
Twin zygosity tests might be occasionally needed as evidence in legal situations. If you need a twin zygosity test for legal purposes, please call 1-888-362-2592 for more information.
In a twin zygosity test, the two siblings are tested.
Simple Collection Procedure
Twin zygosity tests usually are performed in-home. We’ll send you a DNA sample collection kit that contains cotton-like swabs and envelopes that you can use to mail your samples back to us. This kit contains detailed instructions for sample collection and shipping. To collect a person’s DNA sample, simply rub the swab against the inside cheek. Send the samples to our laboratorywe will extract DNA from these cell samples and run the DNA test.
We can complete the test within 3 working days after receiving both twins’ samples. Results are emailed as soon as they are released by the laboratory.