One twin, the 'donor' twin, is small and anemic, the other, the 'recipient' twin, is large and polycythemic. The lives of both twins are endangered by this condition.
There are different types of twins, identical and fraternal being the most common. Identical, or monozygotic, twins develop from the same fertilized egg that splits into two. These twins are...
Identical twins, also known as monozygotic twins, share the same egg at conception and are always either both boys or both girls. Fraternal twins, also known as dizygotic twins, come from two separate eggs fertilized at the same time. They could be the same sex or different.
Fraternal twins happen when two different eggs are fertilized by two different sperm (typically, from the same donor) in the same ovulation cycle. They come from two separate zygotes, so they each have different genes. Identical twins are the result of one zygote that splits in two.
Twin, either of two young who are simultaneously born from one mother. Twinning, common in many animals, is of two biological kinds: the one-egg (monozygotic), or identical, type and the two-egg (dizygotic), or fraternal, type.
If you have a twin brother or sister, the two of you are always the same age. There are identical twins, who have the same DNA, and fraternal twins, who are more like two siblings who happen to be born at the same time.
There are two main types of twins. One is identical twins, like Jennah and Sana, and the other is fraternal twins. Let’s learn more about each type. Identical twins develop from a single fertilized egg. Most often, a single fertilized egg will go on to develop into a single infant.