Do you know the difference between fraternal and identical twins?

Fraternal Twins

Fraternal twins are two siblings born at the same time from two different eggs fertilized by two different sperm. They are also known as dizygotic twins.

• Different genetic makeup: Fraternal twins share about 50% of their DNA, just like any other siblings.
• Can be different sexes: Unlike identical twins, fraternal twins can be both male, both female, or one of each.
• Separate placentas: They usually have separate placentas and amniotic sacs.

Essentially, fraternal twins are like any other pair of siblings born at different times, just with the coincidence of sharing a womb.

Identical Twins

Identical twins come from a single fertilized egg that splits into two. This means they share the same DNA and are always the same sex.  

• Same genetic makeup: They are essentially genetic clones of each other.   1. What is Cloning – Learn Genetics Utah learn.genetics.utah.edu
• Always the same sex: Either both male or both female.   1. Fraternal Twins – National Human Genome Research Institute www.genome.gov
• Can share a placenta: Depending on when the egg splits, identical twins might share a placenta or have separate ones.   1. Monochorionic Twins – UCSF Fetal Treatment Center fetus.ucsf.edu

While they share the same DNA, environmental factors and slight differences in the womb can lead to subtle physical differences between them.