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Q: MALE HOMOSEXUALITY - Enviroment versus Biology as cause. Latest evidence? ( Answered 4 out of 5 stars,   2 Comments )
Subject: MALE HOMOSEXUALITY - Enviroment versus Biology as cause. Latest evidence?
Category: Relationships and Society > Gay, Lesbian, and Bisexual
Asked by: johnfrommelbourne-ga
List Price: $8.00
Posted: 28 Sep 2002 05:26 PDT
Expires: 28 Oct 2002 04:26 PST
Question ID: 70077
Working in large one floor buildings with 300-1000 employees over the
last 20 years I have met and worked with a number of gay men and
befriended some. Not the slightest concern for me what a persons
sexual persuasion is as long as they do the job asked. With the few I
have got close enough to to discuss the subject(as in question at
heading) absolutely no-one has indicated that they believe anything
other than they were born the way they are. Still we debate the cause
as to enviroment or biological so I assume there must be a fair amount
of conjecture or eveidence as to the real cause from both angles.
Perhaps it is a  combination of both!! So just what is the latest
views of the experts and which way to they tend to go.  Is there any
gay  man who has actually said yes I am gay because I was conditioned
to be attracted to men via my enviroment. i.e mother gave me dolls to
play with, spent too much time with my sisters and other girls,
coerced/forced into intimate situation with male  in childhood/early
teens and found I enjoyed it, etc etc

 John From Melbourne
Subject: Re: MALE HOMOSEXUALITY - Enviroment versus Biology as cause. Latest evidence?
Answered By: willie-ga on 28 Sep 2002 06:52 PDT
Rated:4 out of 5 stars

The possible causes of homosexuality have been divided into biological
essentialist theory, namely, that homosexuality is genetically
induced, and social constructionist theory, a belief that
homosexuality is environmentally induced  A third and more prominent
theory, the interactive theory, views sexual orientation as being
produced by a mixture of complementary genetic and learned influences.

Much research has been conducted on the biological basis of
homosexuality with interests ranging from brain differences to genetic
linkage studies.

The justification for research into structural brain differences
associated with sexual orientation has mainly come from rat studies.
Several regions in the rat hypothalamus are sexually dimorphic-ie they
are larger and contain more cells in one sex than another. The sexual
dimphorism of these structures suggest that these brain structures
have a major role in sexual and reproductive functions between the
sexes. Lesioning of the nucleus within the hypothalamus in male rats
has been reported to produce lordosis (a condition that causes the
back to arch) and to affect libido. The rats with this condition
allowed themselves to be mounted, which is interpreted as rodent
homosexual behaviour.

Recent brain research has found structural brain differences in the
hypothalamus in relation to biological sex and sexual orientation in
humans. Differences in size and cell number of various nuclei in the
hypothalamus for homosexual versus heterosexual men have been

The research mentioned above has resulted in excitement as well as
skepticism and has not been verified as of yet. It concludes that
limitations of the data and different scientists different
interpretation of the data suggests that we need replicated and
extended findings before a link between brain differences and
homosexuality can be made.

Many studies have taken place on the environment in which homosexuals
are brough up. These have  shown that  predominately homosexual men
had brothers of whom 22 percent were also homosexual. In contrast,
only 4 percent of the brothers of  heterosexual men were homosexual,
which is about the population average of homosexuality.

In December of 1991, Michael Bailey of Northwestern University and
Richard Pillard of the Boston University School of Medicine  published
a study of homosexuality in twins. They surveyed homosexual men about
their brothers, and they found that of the homosexuals who had
identical twin brothers, 52 percent of those twins were also
homosexual. 22 percent of those who had fraternal twins said that
their twin was gay, and only eleven percent of those who had adopted
siblings said that their adopted brothers were also homosexual.

Bailey and Pillard attributed the differences in these percentages to
the difference in the amount of genetic material shared. Since
identical twins have the same genetic code, they are far more likely
to share sexual orientation than fraternal twins. In other words, they
were born homosexual.

(A frequent objection is these studies is that parents treat identical
twins more similarity and this similar treatment could explain
similarities in behaviour, rather than the twins’ similar genotype.
Also, these studies are frequently run by advertising for volunteers.
It is thought that gay men whose twins are also gay would be more
willing to volunteer than gay men with heterosexual twins.)

Other studies have shown that highest rate of homosexual orientation
was in brothers, who had a 13.5 percent chance of being gay. Analyses
also showed an excess of gay uncles and male first cousins on the
maternal side compared to the paternal side.  It has been suggested
that this shows there is an X-linked (female) gene influence on male
sexual orientation.

One study selected 40 pairs of homosexual brothers in whose lineage
they could identify at least one maternal homosexual relative. They
obtained blood samples from the brothers and from the other family
members. The DNA samples were typed for 22 genetic markers spanning
the length of the X-chromosome.  5 "marker" genes on the X-chromosome
were similar for 33 of the 40 pairs of brothers. This was
statistically different from the expected rate, suggesting that a gene
influencing male homosexuality. This result has only been seen once,
and more studies will be needed before it becomes anything close to

All of the above work has sought to prove a genetic link to male
homosexuality, but none as yet has achieved scientific validity.
Researchers around the world are currently trying to reproduce the
findings, and it may be that, in time, a genetic correlation will be

P-FLAG ("Parents and Friends of Lesbians and Gays") offers a booklet
on the biological research into the origins of homosexuality.
This pamphlet says:

"To date, no researcher has claimed that genes can determine sexual
orientation. At best, researchers believe that there may be a genetic
component. No human behavior, let alone sexual behavior, has been
connected to genetic markers to date...sexuality, like every other
behavior, is undoubtedly influenced by both biological and societal

The best overall summary of most respected researchers is that
homosexuality (like most other psychological conditions) is due to a
combination of social, biological, and psychological factors. Most
researchers are in agreement that demonstrating that any behavioral
state, let alone one so complex, and diverse in its manifestations, as
homosexuality, is not only biological, but genetic is well beyond our
present research capacity

For a full rundown on all the biological research read the following 

A scientific paper on the Biology of human homosexuality psych_375_sample_paper.rtf 

A fine article on the history of scientific research into

On the Origins of Homosexuality 

Search Strategy
johnfrommelbourne-ga rated this answer:4 out of 5 stars
Thanks Willie, You did  very well and I got my money's worth.  I wrote
question before realizing there was a $200 question that was responded
to via the same type of info I was seeking and that you pursued in
your response. That response(to the $200.00 question)was  more
comprehensive than your response but so it should have been for 25
times the fee I paid you!!! There was just one minor point you did not
touch on otherwise five stars so I have given 4 but I mean 4.5. Thanks
again. Just about to jump on plane now to Indonesia then Germany for a
month or so so bye bye till then

Subject: Re: MALE HOMOSEXUALITY - Enviroment versus Biology as cause. Latest evidence?
From: dianna22-ga on 30 Jul 2003 03:36 PDT
willie-ga seems to be confusing research done in Holland into the
biological origins of Transsexualism, with sexual orientation, there
is no link between the BSTc and homosexuality, this is to do solely
with transsexualism
Subject: Re: MALE HOMOSEXUALITY - Enviroment versus Biology as cause. Latest evidence?
From: jake1234-ga on 10 Nov 2003 14:36 PST
All the above studies are commented on the book Coming Out Straight by
Richard Cohen.

If twins have identical genetic structures, i would think that both of
the twins would be gay 100% all of the time instead of 50%, other wise
it would be logical to think that genetics are the deciding factor. 
Second this study was done in strong gay populations.

Also these same researchers have commented that their studies were not
conclusive. Their further comments on their own research can be found
in COS also. (This is the shocking part. What themselves admit.)

Humans are just plan NOT rats or whatever else there is.

As to whether any gays will admit to being conditioned environmentally
to be gay, there are thousands. You can read some posts at

I too can trace back many of the steps leading to my development of
same-sex attraction. Not all people have the same things happen to
them but similar reactions and consequences. I was raised in an
abusive home. but not all are raised in an abusive home. I was raised
by my mother and grandmother and longed for my father to come save me.
I would fantasize about my father or possible fathers and how he would
give me the love and attention i wanted and deserved. I later
sexualized these needs as i got older however, not on purpose. It was
gradually.  Some however have 2 parent in the household but have a
distant father. I don't understand this psychology as much but many
have experienced it.

Also there is no one cause of homosexuality. There were different
things that can happen in a child's life to cause them to develop as

As a young person, my parents also frequently embarassed me about
being attracted to girls so i decided i would never marry and that
marriage and sex were wrong and not for me.

However, it must be explained that not all homosexual under what
caused their SSA. Some will say they are gay as far back as they can
remember. Some have been helped to see some of these influences.
However, i was not. I have been able to trace these things back for
years. I just didn't know help was available because i thought
everyone believed that you can't change. After reading the books i did
discover some new things. the PCC pages were as it they were written
to me personally. I could relate to about 90% of it and was very
shocked at how much others understood how i felt. If you go to that
site or read the book Coming Out Straight. You will have all the
information you need if you are just doing research and are not gay
yourself. If you are gay there is many more things out there.

PCC refers to

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