It is a staple of crime fiction: someone's fingerprints have been found at the scene when it is certain that the suspect with those unique prints could not have been there. Later it is revealed that – unbeknown to the readers/viewers and the fictional detectives – the suspect has a long-lost identical twin; thus explaining how the fingerprints came to be at the crime scene.
After all, 'identical' twins are monozygotic and so develop from the same fertilised egg, and so have the same genome. It is because their genetic 'instructions' are the same that they develop to be so similar in appearance.
However, 'identical' twins are not identical, but just very similar. And fingerprints, although in one sense under genetic control like other aspects of development, are not determined by the genome. The genes provide a template for development, but details arise in the context of developing within the wider environment – so a person's gene may predispose them to have thick hair, but that does not determine the precise number of hairs on their head. An extreme case would be someone with genes 'for' being tall, but who being seriously malnourished through childhood does not reach average height.
So monozygotic twins have unique fingerprints -and other differences in fine detail – such as moles or freckles – that are not easily noticed from a distance.
Read about the nature of alternative conceptions
Read about some examples of science misconceptions
Read about historical scientific conceptions
