Why do identical twins have different fingerprints?

Although identical twins share the same DNA, they don’t look identical cell-for-cell, because not every aspect of your physical appearance is rigidly determined by your genes. Fingerprints are formed semi-randomly as the foetus develops in the womb andare affected by such things as chance fluctuations of hormone levels. Similarly, the pattern of freckles and moles on the skin is caused by random mutations and will vary between identical twins.