A mum from Pennsylvania, in the US gave birth to twins and couldn't believe how different they looked four months later.

Twins can show obvious differences in their physical appearance despite being offspring from the same pregnancy and one mom ...

Find out everything you've always wanted to know about identical twins – from how they form to what makes them unique.

Kim Perell says it was hard growing up with a twin sister. She encourages her twins to be individuals and not compare ...

The author (not pictured) married an identical twin and had fraternal twins. Courtesy of the author I had an emergency C-section and gave birth to my twins early at 35 weeks.

By comparing identical and fraternal twins, researchers can estimate how much of a trait comes from genetics and how much from the environment. Studies of identical twins, in particular, allow ...

The author (not pictured) married an identical twin and had fraternal twins. Courtesy of the author I had an emergency C-section and gave birth to my twins early at 35 weeks.

Identical, or monozygotic, twins develop from the same fertilized egg that splits into two. These twins are the same sex and share the same genes.

Identical twins do not share identical fingerprints. Fingerprint patterns are developed early during pregnancy, and the environment of the womb has a lot to do with how the prints are shaped.