Do fraternal twins have identical DNA?

Fraternal twins are really just siblings who share the same womb. Each starts out as a separate egg fertilized by a separate sperm. They don't share any more DNA than do any two siblings. Siblings normally have 50% of their DNA the same. read more

Identical twins have identical DNA on their inception (that is why they look like carbon copies of each other as the variation is negligible on birth) but as time goes on, they accumulate epigenetic changes (changes caused due to the environment) that cause variation in their DNA leading to them to gain some changes. read more

This is why identical twins can have differing fingerprints. Another big factor why identical twins aren't necessarily completely identical is the environment which each of them were raised in. But for the most part, basic biology says identical twins share the same DNA. read more

Identical, or monozygotic, twins may or may not share the same amniotic sac, depending on how early the single fertilized egg divides into 2. If twins are a boy and a girl, clearly they are fraternal twins, as they do not have the same DNA. A boy has XY chromosomes and a girl has XX chromosomes. read more