The second case of semi-identical twins to ever be recorded was identified in Brisbane, Australia. This case has sparked scientists’ interest even more because, in this case, the twins were discovered during pregnancy. After a series of tests to study this midway phenomenon between identical twins and fraternal twins, researchers have confirmed the case.
The Case of Twins
Pregnancy is a marvel, and the entire process from conception to birth has fascinated both scientists and laymen alike. For twins, the process takes a different twist, and there are two primary methods by which twins develop. For identical twins, a single egg is fertilized by a single sperm. From there, the ball of cells divides into two balls. These go on to develop into two identical twins with the same identical genes. So, you can have twin girls or twin boys.
The pathway is quite different for fraternal twins. In this case, two different sperm fertilize two different eggs. As a result, these twins are not identical, and their genes are as different as those of siblings from the same parents born during different pregnancies.
The middle ground between fraternal and identical twins is semi-identical twins otherwise known as sesquizygotic twins. In the Australian case, the boy and girl twins were born to a mother of 28. They are four years old this year. Their amazing story was first detected when their mother was having her ultrasound performed during the pregnancy. At first, it seems as if the mother was expecting identical twins because of the presence of a shared placenta. Months later, the discovery that the twins were a boy and girl launched the beginning of tests to find out what was happening. Dr. Michael Gabbett, from Queensland University of Technology, and some colleagues tested samples from the amniotic sacs and confirmed the different genetic makeup. Their study can be found in a February 2019 edition of the New England Journal of Medicine.