Dig this permanent imprinting where at a particular age you develop a
discust at having sex with those around for the first six years of
life. Incest is an instinct but it is permanantly imprinted by the
environment. Some people can develop habits & thought processes that
ignore the digust and have sex with their siblings and parents, can
you?

Incest taboos are among the universals of human social behavior. The
avoidance of sexual intercourse between brothers and sisters and
between parents and their offspring is everywhere achieved by cultural
sanctions. But at least in the case of the brother-sister taboo, there
exists a far deeper, less rational form of enforcement: a sexual
aversion automatically develops between persons who have lived
together when one or all grew to the age of six. Studies in Israeli
kibbutzim, the most thorough of which was conducted by Joseph Shepher
of the University of Haifa, have shown that the aversion among people
of the same age is not dependent on an actual blood relationship.
Among 2,769 marriages recorded, none was between members of the same
kibbutz peer group who had been together since birth. There was not
even a single recorded instance of heterosexual activity, despite the
fact that the kibbutzim adults were not opposed to it. Where incest of
any form does occur at low frequencies in less closed societies, it is
ordinarily a source of shame and recrimination. In general, mother-son
intercourse is the most offensive, brother-sister intercourse somewhat
less and father-daughter intercourse the least offensive. But all
forms are usually proscribed. In the United States at the present
time, one of the forms of pornography considered most shocking is the
depiction of intercourse between fathers and their immature daughters.

What advantage do the incest taboos confer? A favored explanation
among anthropologists is that the taboos preserve the integrity of the
family by avoiding the confusion in roles that would result from
incestuous sex. Another, originated by Edward Tylor and built into a
whole anthropological theory by Claude Levi-Strauss in his seminal Les
Structures Elementaires de la Parente, is that it facilitates the
exchange of women during bargaining between social groups. Sisters and
daughters, in this view, are not used for mating but to gain power.

In contrast, the prevailing sociobiological explanation regards family
integration and bridal bargaining as by-products or at most as
secondary contributing factors. It identifies a deeper, more urgent
cause, the heavy physiological penalty imposed by inbreeding. Several
studies by human geneticists have demonstrated that even a moderate
amount of inbreeding results in children who are diminished in overall
body size, muscular coordination, and academic performance. More than
one hundred recessive genes have been discovered that cause hereditary
disease in the undiluted, homozygous state, a condition vastly
enhanced by inbreeding. One analysis of American and French
populations produced the estimate that each person carries an average
of four lethal gene equivalents: either four genes that cause death
outright when in the homozygous state, eight genes that cause death in
fifty percent of homozygotes, or other, arithmetically equivalent
combinations of lethal and debilitating effects. These high numbers,
which are typical of animal species, mean that inbreeding carries a
deadly risk. Among 161 children born to Czechoslovakian women who had
sexual relations with their fathers, brothers, or sons, fifteen were
stillborn or died within the first year of life, and more than 40
percent suffered from various physical and mental defects, including
severe mental retardation, dwarfism, heart and brain deformities, deaf-
mutism, enlargement of the colon, and urinary-tract abnormalities. In
contrast, a group of ninety-five children born to the same women
through nonincestuous relations were on the average as normal as the
population at large. Five died during the first year of life, none had
serious mental deficiencies, and only five others had apparent
physical abnormalities.

The manifestations of inbreeding pathology constitute natural
selection in an intense and unambiguous form. The elementary theory of
population genetics predicts that any behavioral tendency to avoid
incest, however slight or devious, would long ago have spread through
human populations. So powerful is the advantage of outbreeding that it
can be expected to have carried cultural evolution along with it.
Family integrity and leverage during political bargaining may indeed
be felicitous results of outbreeding, but they are more likely to be
devices of convenience, secondary cultural adaptations that made use
of the inevitability of outbreeding for direct biological reasons.

Of the thousands of societies that have existed through human history,
only several of the most recent have possessed any knowledge of
genetics. Very few opportunities presented themselves to make rational
calculations of the destructive effects of inbreeding. Tribal councils
do not compute gene frequencies and mutational loads. The automatic
exclusion of sexual bonding between individuals who have previously
formed certain other kinds of relationships - the "gut feeling" that
promotes the ritual sanctions against incest - is largely unconscious
and irrational. Bond exclusion of the kind displayed by the Israeli
children is an example of what biologists call a proximate (near)
cause; in this instance, the direct psychological exclusion is the
proximate cause of the incest taboo. The ultimate cause suggested by
the biological hypothesis is the loss of genetic fitness that results
from incest. It is a fact that incestuously produced children leave
fewer descendants. The biological hypothesis states that individuals
with a genetic predisposition for bond exclusion and incest avoidance
contribute more genes to the next generation. Natural selection has
probably ground away along these lines for thousands of generations,
and for that reason human beings intuitively avoid incest through the
simple, automatic rule of bond exclusion. To put the idea in its
starkest form, one that acknowledges but temporarily bypasses the
intervening developmental process, human beings are guided by an
instinct based on genes.

On Human Nature - Edward O. Wilson 1978
http://www.amazon.com/exec/obidos/ASIN/067463442X/

On Mar 2, 11:56 pm, "Immortalist" yahoo.com> wrote: