What are the 7 different types of Twins?

Malini VK - Infobite  May 15, 2019

What are the 7 different types of Twins?

Identical twins and Fraternal twins are the most common types of twins. However, there are some rare scenarios which makes the human race even more special.

Identical Twins:


- A fertilized egg(ovum) splits and develops two individuals.

- Identical twins share same genes hence they possess a lot of similarities.

- Also called as "monozygotic twins".

- Identical twins are always of same sex.

Fraternal Twins:


- Two eggs are fertilized by two sperms which can be described as two different pregnancy in single birth.

- Fraternal twins are genetically unique children but they share some similarities just like any brother or sister of the same family.

- Also called as "dizygotic twins".

- Fraternal twins can be of same sex or different.


Half- Identical twins:


- A rare condition when two sperms fertilize an egg at the same time.

- Half-Identical twins share identical DNA from their mother but did not get identical DNA from their father.

- It is a type of identical twins where they cannot be differentiated from appearance as their difference is in DNA.

Mirror-Image twins:


- This type of twins has asymmetrically appearing features.

- If twin A possess birth mark on right cheek, twin B has on left cheek.

- The shape or placement of features such as moles, eyebrow shape, eye shape, dimples are opposite so that when they face each other it is like they are mirror reflections of one another.

- Causes for mirror twinning is not medically confirmed.

- It is a type of identical twins where they can be differentiated only from observing physical features.


Mixed-Chromosome Twins:


- Another rare condition where the condition was like fraternal twins initially but early on the pregnancy the two fertilized eggs merge into one resulting in twins with two distinct sets of DNA.

- The eggs won't undergo fusion rather they exchange cells and genetic material during development.

- They may have difference in skin tone, hair, characters, etc.




- It is a condition when there is an occurrence of another pregnancy during an ongoing pregnancy.

- Second ovum is fertilized by a sperm and implanted in the womb days or weeks after the first one.

- They are considered twins since they will be born during the same birth on the same day.

- They won't be identical and can be same sex or different.




- A type of twins where they have different biological fathers.

- Fertilization of two or more eggs from the same cycle by sperms from separate acts of sexual intercourse.

- They won't be identical and can be same sex or different.