However, fingerprints are not an entirely genetic characteristic. Scientists love to use this topic as an example of the old "nature vs. nurture" debate. Fingerprinting, along with other physical characteristics, is an example of a phenotype -- meaning that it is determined by the interaction of an indivdual's genes and the developmental environment in the uterus.

The ultimate shape of fingerprints are believed to be influenced by environmental factors during pregnancy, like nutrition, blood pressure, position in the womb and the growth rate of the fingers at the end of the first trimester. Thus, you will find similar patterns of whorls and ridges in the fingerprints of identical twins. But there will also be differences -- just as there are differences between the fingers on any individual's hands.