Twin Zygosity DNA Testing

Determining whether twins are identical or fraternal is not always easy. Identical (monozygotic) twins are conceived when one egg is fertilized and splits into two separate cells resulting in twins with identical copies of DNA. Fraternal (dizygotic) twins are conceived when two eggs are released during ovulation and fertilized by separate sperm cells resulting in twins with different DNA profiles.

Modern day medical advances have made it possible to examine and map out the DNA profiles of individuals. Through this kind of testing, DNA profiles from twins can be compared to determine whether they have the exact same DNA profiles, meaning they are identical twins, or whether they differ, meaning they are fraternal twins. These DNA tests have now become accessible for home use and Twin Zygosity DNA Testing is now a viable and affordable (as cheap as £139.00) solution to determining what kind of twin relationship is shared between two (or more) individuals.

Identical twin occurrences are about half as common as fraternal. A very rare phenomenon which may also occur – called Heteropaternal superfecundation – happens when two eggs are released during ovulation which are fertilized by sperm cells from two different men in a short period of time; resulting in twins being born with two different biological fathers.


Although the most common reason for carrying out these tests is to satisfy parental curiosity, they can also be used for checking compatibility in situations where organ or bone marrow donations are needed, since identical twins will have less chance of organ rejection if one identical twin donates to another. Many parents are given incorrect information about their twins by doctors at the time of birth since doctors examine the placenta. Examination of the placenta done by obstetricians is not very accurate and can result in misinformation. This examination is done by inspecting the placenta membrane thickness or how easily it can be peeled apart. This kind of testing only tends to be accurate under microscope examination – which is often very expensive, and still not as conclusive, as twin zygosity DNA testing.

Twin zygosity DNA tests can be carried out at home, without the involvement of a medical professional, by means of DNA sample collection through the use of oral swabs. These cotton swabs are rubbed on the inside of the mouth for 10 seconds and allowed to dry for an hour before being safely packed and sent to the labs for testing. Advanced labs such as those at easyDNA have state of the art genetic identification systems that analyze DNA through 16 different genetic markers. These systems ensure maximum accuracy and guarantee minimum probabilities in excess of 99.99%.

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