Studies have discovered that parents or twins who were mistaken in their beliefs about zygosity were often misled by incorrect advice from parents or medical professionals, or they made their own inaccurate assumptions. There are several myths associated with twin zygosity, including:
- All same-sex twins are identical: This is not true because same-sex twins can be either identical or fraternal. Zygosity should be determined through DNA testing to be certain.
- All twins with separate placentas are fraternal: While separate placentas often indicate fraternal twins, some identical twins can also have separate placentas, making it an unreliable indicator of zygosity.
- All IVF-conceived twins are fraternal: IVF-conceived twins can be either fraternal or identical, just like naturally conceived twins. Zygosity testing is the only way to confirm.
- Identical twins must look exactly alike: Identical twins may look very similar, but they can still have differences in appearance due to factors like environmental influences and random genetic variations. It’s not necessary for them to look identical to be considered identical twins.