Hi, I recently put this in the Other-Science section but this seems this is a more appropriate section.
I heard in discovery that all our body parts get replaced. So why do fingerprints stay the same? Also why do tattoos stay the same?
Colin
Favorite Answer
Your particular pattern of fingerprints are not "due to your genetics." If this were true, identical twins would also have identical fingerprints; they do not. However, while your fingerprints are unique to you, they do actually change (gradually) over time, usually due to wear and tear to the ends of the fingers or permanent scars.
Tattoos actually are inorganic inks placed within the dermis (not under it), but have you noticed that tattoos usually become a dark green color over time? What actually happens is most tattoo inks are gradually removed from the skin over time, but additionally their presence causes permanent pigment production rate changes to your pigment producing skin cells, which cause the skin to be darker after the tattoo inks are degraded.
Gary H
It is related to genetics but it is not true that they always stay the same. For one thing, they are a different size when you are born because your fingers are small.
Your genetics and the variability in exactly how the cells develop in utero determine how your skin cells grow and that is what determines the "finger prints" you start with. Obviously if you suffer a serious injury to your fingers, scar tissue can certianly change the finger prints.
As far as the "replacement"... The top layer of our skin is dead and rubs off over time (which is why having dust mites eating those dead skin cells in your carpet and in your furniture is part of life). Since the skin grows from the inside, it is "pushing" the dead cells out. In your other organs, the replacement of dead or injured cells is more like just replacement.
The ink that is injected into you to make a tattoo is deep enough that it is not carried to the surface as your skin cells grow, die, and rub off.
Anonymous
Your fingerprints are due to your genetics and therefore never change. The cells that replace them follow your relevant code as to where to go and go in the same place the old cells went. It's just like your eye colour doesn't change during your life.
Tattoos are a series of ink dots placed just under the skin, and are not a part of our genetics. They are also not organic. So they are not replaced and remain under your skin throughout your lifetime.