Epigenetics, more than genes
inherited/passed on
(Top Posts - Science - 101907)

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A PBS Special, broadcast last night, "Ghost
in Your Genes", discusses the dramatic role
that gene switches (called epigenes) play in
inheritance -and- in behavioral impacts on
gene switches.

Web page
  http://www.pbs.org/wgbh/nova/genes/

This is a rather complex topic, and you may
not be able to pick up on its significance by
reading the following, but it's my best first
effort at trying to explain the manner in which
gene switches function, as best I understand
it based on my initial exposure to the topic.

To sum up a few of the early findings:

  o The inherited switches you received from
     your paternal grandfather and grandmother
     and your maternal grandfather and grand-
     mother were impacted by conditions pre-
     sent at different stages of their development,
     and those conditions impacted the manner
     in which your own gene switches (epi-
     genes) behave

  o In rats, the degree of nurturing a mother
     gives her offspring directly impacts the
     gene switches which determine how the
     offspring react to stress during their lives;
     in theory, this resembles how behavioral
     abnormalities (such as rejection, child
     abuse) would result in changes to gene
     switches which adversely impact the
     health and behavior of children over
     their entire lives

  o Identical twins, with identical genes, at
     times have dissimilar genetic conditions,
     explainable by the manner in which gene
     switches differ even among individuals
     with identical genes

  o Gene switches are impacted by aging and
     by environment, including (as indicated
     above) the social support/neglect/abuse
     environment a child is raised in

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In essence, with the impact of environment on
genetic switches, the Nature + Nurture equa-
tion includes the impact of Nurture, not only
on the child, directly, but also on the child's
ancestors and their ancestors' gene switches
which have been passed down to the child.

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