Studies into the causes of sexual orientation have mainly concentrated on
males. All of
the studies show that genes play a significant role in determining
homosexual orientation. None of the studies show that the environment is
solely responsible. We did not pick and choose the studies which are
reported here. We have reported all that we have found, regardless of
Studies on monozygotic twins: These are twins that resulted
from the splitting of a single fertilized egg -- the zygote -- into two
separate zygotes with identical genetic structure. They are commonly
called "identical twins." Studies have been made which
involve relatively rare cases in which identical twins were separated at birth and have not been in
contact since. Studies consistently show that male homosexual
orientation is mainly (perhaps entirely) determined at conception by a
person's genes. This is such an important and definitive study
describe it in more detail in separate multi-part essay.
Suicide implications: The National Institute of Health (a US Federal Government agency) reported that as
30% of youth suicides are by gays and lesbians. Since only about 5% of the population identifies as lesbian or gay, this means that LGB youth commit suicide at a rate as high as six times the normal value. These are
committed by youth who are certain that they will remain gay or lesbian for the rest of their
lives. Many, probably most of these young
people who complete a suicide attempt had been taught by their
families, religious institutions, schools etc., starting at a very early age, to hate or reject
homosexuality. If they had any hope of changing their
orientation, they probably would seek counseling instead of killing themselves. Most
probably believe that their sexual orientation was genetically caused
and is unchangeable.
Introspection: Most sexually active adults are aware that their sexual orientation is not chosen and
not changeable. Assuming that you are a heterosexual:
Consider how you would change yourself so that you become sexually attracted to a person
of the same gender. You will realize that it is quite impossible to create feelings of
sexual attraction if they do not currently exist.
Consider at what age you chose your sexual orientation? You will realize that, as far
back as you can remember, you were either asexual or heterosexual.
Irrationality of choice: In the forward to the book "We Were Baptized Too: Claiming God's Grace for
Lesbians and Gays", Anglican Archbishop Desmond Tutu of South Africa wrote:
"Someone has said that if this sexual orientation were indeed a matter of personal
choice, the homosexual persons must be the craziest coots around to choose a way of life
that exposes them to so much hostility, discrimination, loss, and suffering." 13
Brain Structure: Simon LeVay, a Neuroanatomist at the Salk Institute in California published a study
in 1991 which examined the brains of men who had died of AIDS. He found that the INAH 3 (a
structure within the hypothalamus) differed in size between heterosexual and homosexual
men. This suggested to the researcher that "sexual orientation has a biological
substrate". 2 This study has been criticized on a number of grounds. Many of his
subjects died of AIDS; perhaps the difference in structure size was caused by the disease,
or the medications that they took, rather than the person's sexual orientation. Others have
suggested that homosexual or heterosexual activity may have determined
the size of the structure, rather than vice-versa. In spite of these weaknesses, the study has wide acceptance among human sexuality researchers.
Hearing: A group of researchers at the University of Texas found
structural differences in the inner ears between
lesbians and heterosexual women. On average, women have more sensitive cochlea amplifiers
than men; they are able to detect softer sounds in a very quiet room. The researchers found
that lesbians had inner ear characteristics that were more like those of men. The
structure of the inner ear forms before birth and is affected during pregnancy by
androgens. 7 These findings indicate
that the sexual orientation of females is at least partly decided before birth -- perhaps at conception.
Incidence: Gays and lesbians do not appear to be any less common in societies which condemn and
suppress homosexuals; they do not seem to be any more common in accepting societies.
They also seem to be equally common in countries where parenting styles are very different. This would argue against sexual orientation being learned from the
Parenting: Almost all children raised in families headed by two gays or two lesbians grow up
heterosexual. The sexual orientation of one's parents, and any associated parenting styles appear to have little or no
influence over the orientation of their children.
Infection: A new theory has been proposed that homosexuality is
caused by a bacteria or virus. It is not a highly regarded theory by researchers. This also would argue against sexual orientation being learned from the
Epigenetics: This is a recent field of research of how gene expression is managed in individuals by temporary switches known as " 'epi-marks.' ... Sex specific epi-marks generally do not transfer between generations and are considered 'erased.' There are some indications that homosexuality can result when these marks are not 'erased' but are passed on from father to daughter or mother to son." 12 The theory suggests that this process may produce daughters with typically male sexual attraction or males with typically female attraction.