Once the identical twins reached the age of 50, there was an increased similarity in the number of pairs of individual moles.

BBC: Twins offer skin cancer clue

The researchers were surprised to find that the degree of similarity in the number of moles increased with age - even when the subjects were exposed to different environmental factors.

BBC: Twins offer skin cancer clue

The other reason is that declaring a match between two prints generally requires a certain number of points of similarity between them.

ECONOMIST: Fingerprint evidence

Unfortunately, the validity of this process, and the number of points of similarity needed to make it statistically secure, have not been scientifically investigated.

ECONOMIST: Fingering fingerprints | The