6 doctors weighed in:

What are the types of twins?

6 doctors weighed in
Dr. Keith Stockerl-Goldstein
Internal Medicine - Hematology & Oncology
3 doctors agree

In brief: Identical/fraternal

Identical twins occur when a fertilized egg splits and results in 2 individuals with the same dna and same gender. Fraternal twins come from 2 separate fertilized eggs.
They do not have the same dna and can be the same or opposite gender.

In brief: Identical/fraternal

Identical twins occur when a fertilized egg splits and results in 2 individuals with the same dna and same gender. Fraternal twins come from 2 separate fertilized eggs.
They do not have the same dna and can be the same or opposite gender.
Dr. Keith Stockerl-Goldstein
Dr. Keith Stockerl-Goldstein
Thank
Dr. John Comisi
Dentistry
1 doctor agrees

In brief: Three types possible

Identical, fraternal, and semi-identical twins.
Identical twins, one egg is fertilized and then splits, forming two identical embryos. For fraternal twins, two separate eggs are fertilized by one sperm each, forming two embryos. Semi-identical twins (a new possibility) can occur when one egg is fertilized by two different sperm. Not a widely accepted concept, but it is a possibility none the less.

In brief: Three types possible

Identical, fraternal, and semi-identical twins.
Identical twins, one egg is fertilized and then splits, forming two identical embryos. For fraternal twins, two separate eggs are fertilized by one sperm each, forming two embryos. Semi-identical twins (a new possibility) can occur when one egg is fertilized by two different sperm. Not a widely accepted concept, but it is a possibility none the less.
Dr. John Comisi
Dr. John Comisi
Thank
Get help from a real doctor now
Dr. Adam Levy
Board Certified, Obstetrics & Gynecology
34 years in practice
1M people helped
Continue
108,000 doctors available
Read more answers from doctors