If the two babies are of different genders, then it’s quite easy to know that they are dizygotic twins. However, it might not be as easy to determine if the two babies are of the same gender.

Fraternal or dizygotic twins develop from two different eggs fertilized by separate sperm; ... Mixed-gender twins are the most common type of fraternals, some 50 percent are boy-girl.

Identical, or monozygotic, twins develop from the same fertilized egg that splits into two. These twins are the same sex and share the same genes. Sometimes called paternal twins, identical twins ...

There have been some rare cases where identical twins have been of different sexes. Such cases happen when one twin loses a Y chromosome after the zygote splits. Remember that sex and gender don't ...

Different experiences in the womb. Although they share a womb, identical twins often experience it differently. One might have better access to nutrients or more room to grow.