What are the differences between fraternal and identical twins?

In a nutshell, the two most common types of twins are identical and fraternal. Sometimes there are obvious ways to tell which type is what, but there are some complexities with determining the zygosity of same-sex twins - let's get into it.

Twins and multiples are usually described according to:

  • how many eggs they develop from – one or two
  • if they share a placenta in their mother’s womb

The most common types of twins are fraternal twins and identical twins. There are other types of unusual and atpyical twins such as chimaeric twins, mirror image twins, polar body twins, fetus papyraceus and more! Check out this article written by our Patron, Professor Mark Umstad, on some of the rarer types of twins.

Back to Frequently Asked Questions FAQ