Re: DNA has strongest influence on phenotype

From: Michael Ragland (ragland37_at_webtv.net)
Date: 08/21/04 

Date: Sat, 21 Aug 2004 16:42:07 +0000 (UTC)

dkomo:
I was saying something like this: "How important is the environment in
which an embryo develops as compared to its DNA in determining its
phenotype? It can't be that strong of a factor because otherwise
fraternal twins, even though they have different genotypes, would turn
out to be closer to each other phenotypically than they normally do. In
fact, it appears that DNA has by far the strongest influence on
phenotype, for both fraternal twins and identical twins, even though
they develop in identical environments. This is not to deny that
environment can determine *some* phenotypic traits."

Ragland:
Yes dkomo and I essentially stated the same argument in much abbreviated
form to Mr. Hoelzer. I stated to him, "Despite the differences in
environments this is indicative DNA has by far the strongest influence
on phenotype. You yourself stated, "All in all, I don't find the "eery"
similarity of maternal twins surprising, given the extent of shared
information sources from both genomes and environments (and physics)."
Mr. Hoelzer replies, "Right, and given that there are three sources of
shared information it is raw speculation to claim that any one of them
has more influence on the extent of similarity than any other. I counter
responded, "Well if the shared environment and physics was similar but
they weren't genetically identical I think the product would be much
more dissimilar. This is analogous to you saying, "It can't be that
strong of a factor [the environment] because otherwise fraternal twins,
even though they have different genotypes, would turn out to be closer
to each other phenotypically than they normally do.

"It's uncertain whether intelligence has any long term survival value.
Bacteria do quite well without it."
 Stephen Hawking

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