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From: Leonardo Villagran <leo.villagran@utoronto.ca>
Subject: Re: Fingerprints and Identical Twins
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Date: Sun, 16 Feb 1997 21:44:19 GMT
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Anthony Q. Bachler wrote:
> 
> Fingerprints are determined by genetic influence over environmental
> factors.  The environmental factors have more to do with them though.  Just
> because the two offspring have the same genetic code does not mean that
> they are identical in every way.  Small disimilarities in the cellular
> surface structures can create differences large enough to change the
> fingerprints.  Similiar microstructural differences can be found in other
> areas of the body such as organ shapes and veinus formations.
> 
> Michael Hutto <mehutto@mindspring.com> wrote in article
> <3303e746.1697763@news.mindspring.com>...
> > Could someone explain to this non-geneticist why identical twins - who
> > share the same DNA and genetic patterns - would have different
> > fingerprints?
> >
> > It is my understanding that identical twins will have similar, but not
> > identical, fingerprints.  How could this be?  Are fingerprints not
> > genetically determined? If they are not, what determines the
> > particular pattern?  Environmental influences?
> >
> > Please respond via e-mail and thanks in advance!
> >

What you guys are referring to is the concept of phenotypic 
plasticity.  A good example of a phenotypically plastic trait is 
height.  Height is not strictly determined by your genes, rather your 
predisposition to a certain general stature is (tall, average, short).
Environmental factors, such a nutrition, play a key role in the 
expression of the trait.  A "genetically short" individual could be 
exposed to environmental factors which optimize growth, and end up 
taller than a "genetically tall" individual who was chronically 
malnourished...  This is especially well documented in plants (as they 
make ideal subjects fore genetic study):  you take cuttings from the 
same plant (as such, they are genetically identical) and situate them 
in different environments.  The differences in the various cuttings' 
growth illustrates the effect of environment on plastic traits.  
"Life(4th ed.)" by Purves et al. makes a good read for genetics;  
it'll give you a good over-all grock for it, without bogging you down 
in a quagmire of biochemistry.  
-- 
Leonardo Villagran
University of Toronto
Toronto, Canada
leo.villagran@utoronto.ca
