Body & HealthFact
Your fingerprint was finished before you were born.
The first ridges form from about week 13 of pregnancy, and the final pattern is set around week 15. Genes fix the basic type, but small environmental influences in the womb account for roughly 5 percent of the variability. That's why even identical twins have very similar but not identical prints.
Useful: Identical genes don't mean an identical body – development rolls dice too.
Source: en.wikipedia.org