zeb haradon wrote:
>
> >From: Spike Jones <spike66@ibm.net>
> >Reply-To: extropians@extropy.org
> >To: extropians@extropy.org
> >Subject: Re: Gay Extropians!!!
> >Date: Fri, 06 Oct 2000 20:25:56 -0700
> >
>
> >After quietly listening to the exchange on this topic, I submit this
> >notion:
> >that there is some yet unknown mechanical/genetic explanation for
> >homosexuality that is a completely random event. It comes from inheriting
> >the genital configuration from one parent and the sexual orientation
> >from the other, and that the probability of this is about 5% regardless
> >of other factors. I have had gay friends tell me they were gay since
> >as far back as their earliest memories, cases where twin boys were
> >raised identically as far as anyone could tell, yet only one is gay. It
> >must be something genetic, decided at the moment of conception.
>
> Something striking I remember reading is that the correlation between
> homosexuality between two identical twins is almost exactly 50% (if one twin
> is gay, his twin has a 50% chance of being gay..) and that for non-identical
> twins and for just plain brothers, it is about 25%. This tells me that the
> influence is 50% of genetics and 50% social/environmental/whatever
> (non-fraternal twins share 50% of their DNA - 50% x 50% = 25%).
Actually, this 25%/50% is what you would expect if it were totally genetic,
since fraternal twins are caused by fertilization of two eggs (which themselves
have a 50% chance of commonality) by two sperm. This, I think, also suggests
that homosexuality manifests as the reinforcement of two recessives, one from
the male, the other from the female. This data would be reinforced if you took a
group of straights with one of four siblings being gay, and bred them, you'd get
a 25% output of gay offspring, with 50% having the recessive (assuming that all
of the parents started out with the recessives. If 33% did not have the
recessive (which you'd expect from such a Mendel ratio), you'd wind up with
16.5% gay, 33% straight w/ gay recessive, and 50% straight with no recessive).
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