Glenn,
The twin studies anecdotes you provided are indeed fascinating and
eye-catching. However, the data is alot more complicated than that, and many
researchers are concern about this being misinterpreted as genetic
determinism. the concordance rates between MZ twins are typically in the .50
range for many personality traits, while DZ twins are in the .30 range,
suggesting a significant genetic component (see Plomin, Chipueer, & Loehlin,
1990). A correlation of .50 is actually moderately low, considering the MZ
twins share 100% genetic material. That amounts to explaining only 25% of
the variance in any trait. Any puzzling finding is that in adoption studies,
the concordance rates for biological siblings (50% in common) and adoptive
siblings (0% in common) show very small differences only, which again
suggest that genetic influence is small, but significant, with regard to
complex behaviors in humans.
You wrote:
<<Such systems allow for free-will to be united with determinism. Our
genetic
system is just such a nonlinear system. We feel perfect free will to
choose
this or that course of action, yet we may be confined to certain
patterns in
our lives which have been fore-ordained by God.>>
What does it mean to choose one course of action over another? Suppose we
use the illustration of choosing a can of Pepsi or Coke. To say that one is
free, does it imply that one is able to make an purely arbitrary and
indepedent choice with no connection to one's past history? That notion of
free will is something I find hard to accept. But if the choice is not
independent, then past or present forces are influencing the decision - and
if so, how is it free?
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