But in extremely rare cases they can in fact stem from one egg, like identical twins lesbian kissing in public. Twins of different genders are universally accepted as a sound basis for a clinical determination that boy and girl twins are not identical.
However, in extremely rare cases, boy and girl twins can stem same the same fertilized egg, like identical twins do. Twins, who stem identical the same fertilized egg, are called monozygotic twins.
Read more about these examples and references. A woman ovulates and releases one egg. The egg is fertilized by a sperm cell now called zygote.
The zygote splits into two within a few days after fertilization. The two zygotes are developing rapidly into two embryos that have the same chromosomes and genes. However, although they share the same genetic characteristics, identical twins are not necessarily sex alike.