Identical twins (also called monozygotic or MZ twins) are conceived when a single sperm fertilizes a single egg and the resulting zygote divides in two. Because the zygote originated from the same ...

Those kids could be identical twins—kids of the same sex developed from a single zygote that splits and forms two embryos. They could also be fraternal twins, which are developed from a separate ...

Within hours of fertilisation, this new cell, called a zygote, divided into two identical ... the embryos create near-replicas of themselves. Identical twins. This quirk of nature has given ...