"Nobody in science now believes that sexual orientation is caused by events
in adolescence...Homosexuality is an early, probably prenatal and irreversible
preference." Author and geneticist Matt Ridley
1
"Often, one's 'homosexuality' is thrust upon him by childhood molestation,
poor familial relations, or general peer harassment during the adolescent years,
including the continual calling of that child 'gay'." Parents Rights Coalition,
a conservative Christian agency in Massachusetts. 2
"The only choice involved with being gay is when a person decides
between living in the closet and hiding behind a facade, or deciding to accept,
acknowledge and BE who they are." Author Kevin Schattenkirk, who is himself gay.
3
"Homosexuals... tell of rejection from early childhood and lack of bonding
to same-sex parents, sexual violence and rape, or mental and emotional abuse as
critical elements in the formation of their gender-identity" From an
advertisement by the American Family Association, Christian Coalition,
Concerned Women for America, Family Research Council, and many other
conservative Christian groups.
4
Overview:
Religiously conservative information sources generally reject the belief that
homosexuality is caused or set up by genes. Information sources sponsored by
gays, lesbians, religious liberals, mental health professionals and human
sexuality researchers generally stress the genetic cause of sexual orientation.
We have described a number of studies which show that the propensity towards
homosexuality is traceable either to:
Genetic causes at conception, or
Environmental causes in the womb before birth.
We are always watching for new studies into this phenomenon. We have found
none that contradict the above conclusions.
A number of studies on identical twins have indicated that perhaps 10% of
people are born with the genetic predisposition to develop a homosexual
orientation in adulthood. However, this predisposition may or may not be
triggered, either before birth or during early childhood by a factor in the
environment which is currently unknown. Thus, having a homosexual orientation is
not completely determined by one's genes. However, current evidence is that it
is certainly outside of a person's conscious control.
Religious conservatives generally reject these studies. They deny that people
are set up by their genes to develop a homosexual orientation. They generally
believe that gays and lesbians choose their orientation. One psychologist,
Joseph Nicolosi, who is the president of the National Association of Research
and Therapy of Homosexuality (NARTH) teaches that:
Homosexuality can be prevented by proper upbringing of children, and
Adults with a homosexual orientation can become heterosexual through
therapy. 5
This theme has been picked up by the Fundamentalist Christian group,
Focus on the Family. Focus holds "Love won out" conferences
across North America which teach their beliefs that "homosexuality is
preventable and treatable." These beliefs are also found in many other
religiously conservative information sources. 6
Prejudice against gays and lesbians:
Many people believe that prejudice against gays and lesbians will melt away
if the public were to accept the belief that a person's sexual orientation is
mainly determined by genes. The rationale is that if a person is a gay or
lesbian because of their genetic makeup, then their orientation is not a choice;
it is something beyond of their control. This belief appears to be contradicted
by a 1999-APR web-site poll conducted by Time.com. It dealt with "Genetics
and Homosexuality," and asked the question: "Would your attitude towards
homosexuality change if it were proven to be genetically determined?"
Response as of 2000-MAR-6 was: 75% no, 21% yes and 4% not sure.
Also consider that:
The public has known for centuries that skin color is determined
genetically, yet North America still has many racists who automatically hate or
consider inferior anyone whose skin color falls within a certain range.
The public has known for centuries that the sex of a person is determined
genetically, yet North America still has many sexists.
Conservative Protestants typically have an
unshakable belief that the authors of the Bible were
inspired by God and that they produced inerrant text. Further, they interpret the Bible as
implying that everyone is naturally heterosexual. They are unlikely to alter
their beliefs, just because a series of scientific studies indicate otherwise.
The Roman Catholic church teaches that sexual
orientation is beyond a person's control It is neither changeable nor chosen by
the individual. However, the church still urges governments and its own members
to deny some human rights to gays and lesbians, like
the right to marry
Liberals from all religions generally accept the findings of scientific
studies.
Teachings of the conservative wings of non-Christian religions generally
believe that homosexuality is a chosen, unnatural behavior.
Study based on fingertip ridges:
J.A.Y. Hall and D. Kimura at the University of Western Ontario at
London ON Canada found a relationship between the number of fingertip ridges on
men and their sexual orientation.
7 They compared the number of ridges on the index
finger and thumb of the left hand with the number on the corresponding fingers
of the right hand. They found that 30% of the homosexuals tested had a surplus
of ridges on their left hand, whereas only 14% of the heterosexuals did. This is
a particularly interesting finding, because fingerprints are fully determined in
a fetus before the 17th week of pregnancy, and do not change thereafter, through
birth, infancy, childhood, youth and adulthood. This would seem to prove that
for at least some adult homosexuals, their sexual orientation was pre-determined
before birth, perhaps at conception; certainly by the end of the 4th month of
pregnancy. 8,9
A California psychologist, Marc Breedlove, "conducted his research at
three street fairs in the San Francisco Bay area in the fall of 1999." Each
study participant had his or her hand photocopied on a portable copy machine to
record finger length. Participants also filled out a questionnaire on sexual
orientation and birth order. 720 volunteers participated. They found that
lesbians tended to have shorter index fingers (relative to their ring fingers)
than did heterosexual women. They also found that gay males tended to have
shorter index fingers (relative to their ring fingers) than heterosexual males.
The relative size of a person's fingers is determined well before birth. These
findings imply that sexual orientation is at least partly decided before birth
-- perhaps at conception when a person's unique DNA is established.
10
Studies based on fraternal birth order:
In the mid 1990s, researcher Ray Blanchard studied families in which there is
a male child with a homosexual orientation. He found that a gay man is more
likely to have older brothers than older sisters. He found that the probability
that a male child will grow up as a homosexual increases by about 33% for each
brother born before he was. Blanchard suggests that this effect may be caused by
an immune response within the mother during pregnancy.
11,12,13 According to the program 60 Minutes, recent studies
have shown that this effect only happens among right-handed brothers. 28
Sponsored link:
Studies based on existing families:
Psychologist Michael Bailey of Northwestern University and Psychiatrist
Richard Pillard of Boston University studied the sexual orientation of male
siblings raised together since birth. 9 He found
that if one was homosexual then the chance of their sibling being homosexual
was:
Fifty two percent for their identical twin, who shared 100% of the same
genes. This result was essentially identical to the separated identical twin
studies described below. It shows that if one identical male
twin is gay, then the other twin will probably also be gay -- whether raised in
the same family or raised by different families.
Twenty-two percent for their non-identical twin; they share half of the same
genes
About 10% for adopted or non-twin brothers; they share none to half of the
same genes.
This study also points to a very strong genetic factor at the time of
conception. This type of study tends to have the same flaws as in the identical
twin studies
described below. The second twin might not be willing to
admit to being homosexual. One sibling could be bisexual and identify themselves
to the interviewer as a homosexual; the other could also be bisexual and be
behaving as a homosexual.
J. M. Bailey, R. C. Pillard and others conducted a similar study of female
identical twins raised in the same family, in which one twin identified herself
as a lesbian.
14
The results showed that 48% (34 out of 71) of their twins also said that she is
homosexual. Again, a very strong genetic component is indicated.
Dean Hamer, and his colleagues at the National Cancer Institute collected
family data from the families of 114 gay men. 15
They found out which, if any, of their siblings, parents, cousins, uncles etc.
were also gay. They quickly determined that homosexuality runs in families. By
itself, these results show nothing. They might indicate that homosexuality is
genetically caused, or might show that it is caused by upbringing, by some
hormonal levels in the womb or some other environmental factor that appears in
some family lines more than other.
Further studies showed that "There were increased rates of gay people among
family members genetically related to each other even when raised apart in
different households." This reinforced the possibility that genetic factors
might cause people to become gay. However, these observations were not
conclusive; they were merely suggestive.
What proved the genetic nature of "gayness" was a pedigree test. This
type of study examines the sexual orientation of the ancestors of many gay
adults - both on their father's and mother's side. Some possible results from a
pedigree study on Hamer's sample of gay adults would be:
An approximately equal number of gays might be found on the mothers' side of
the family, when compared to the fathers' side. Some gays may have many gay
ancestors on their mother's side, whereas other gays may see the same effect on
their father's side. But when all the results were lumped together, if the total
numbers would be about equal, then the results could point to:
"Gayness" being caused by environmental factors, or
"Gayness" being caused by some gene on a chromosome other than the X
chromosome.
A much larger number of gays might be found on the mother's side of the
family. This would show conclusively that not only was the gene passed
genetically, but that it is located somewhere on the X chromosome - since men
always get their X chromosome only
from their mother. This is called the "maternal effect." It is well known
in genetics.
The researchers found that the second result was observed. A gay male from
the population that Hamer studied would notice that more of his mother's
brothers will be gay than his father's brothers; so too with the various classes
of maternal cousins when compared to his paternal cousins. Thus, much male
homosexuality is caused by a gene on the X chromosome. Hamer went on to find the
approximate location on the chromosome where the gay-causing gene was located.
He found that many of his subjects had an identical sequence on the Xq28 region
of their X chromosome. This shows the approximate location of the "gay gene."
Researchers speculated that a group of interacting genes (including one in this
region) might be found to determine sexual orientation in males. This prediction
came to pass. The statistical "p" value is a measure of the significance of
a test: the probability that it could have happened by chance. P values less
than 0.01 (1%) are considered very significant. The Hamer study had a P factor
of 0.00001, and so is considered extremely reliable.
The DNA of 36 pairs of lesbian sisters were also studied; no corresponding
pattern has yet been found.
The Hamer group's results on gay males must be regarded as tentative:
Dr. Alan Sanders, professor of psychiatry at the University of Chicago
attempted to replicate the results on 54 sets of gay brothers. He announced at
the American Psychiatric Association's
annual conference in 1998-JUN that he was unsuccessful. "No [genetic] marker
data reached statistically significant criteria." The results of the
pedigree test on Sander's subjects is not known.
George Rice's selected subjects from carefully selected families in which
the pedigree test was the reverse of Hamer's: gays were found in the father's
line, not the mother's line. As expected, the markers that Hamer found were not
found by Rice.
16 One might conclude that:
Some gays have many gay ancestors in their mother's line but not in their
fathers' line. This was the group from which Hamer drew his subjects. They share
genes on their X chromosome that apparently can cause a gay orientation.
Other gays have the reverse pedigree pattern: they have many gay ancestors
in their father's line but not their mother's. One would not expect them to have
gay-causing genes on their X chromosome. Rice was unable to find any.
These are twins that resulted from the splitting of a single fertilized egg
-- the zygote -- into two separate zygotes with identical genetic structure. It
can happen at any time prior to about 14 days after conception. They are
commonly called "identical twins." Studying these twins, researchers can
determine whether a trait such as homosexuality is determined by the environment
or by genetics or by a combination of both. The technique involves the study of
pairs of identical twins who were separated at birth and raised in different
families without later contact. Being identical twins, they would have the same
genetic structure. But being raised independently in different families (often
in different states), they would mature (at least after birth) and experience
totally unrelated environments, family types, family sizes, parenting methods,
level of abuse, etc. Fortunately, a U.S. university maintains an index of twins
who were raised separately since birth.
Schizophrenia occurs in about 1% of the adult population. In previous
decades, the disorder was believed to be caused by incompetent parenting.
Studies of identical twins overturned this belief. They showed that if one twin
was schizophrenic, the chances of the other twin having the disorder is 65%.
This shows that schizophrenia has a very strong genetic component. 17
Decades ago, autism was also blamed on the parents. Identical twin
studies turned up similar results: if one twin was autistic, there was a 68%
chance that the other was also autistic. 17 Similarly the
cause of homosexuality has been attributed to lack of bonding between a child
and the same-sex parent. This belief has been abandoned by almost all mental
health professionals. However, many religious conservatives still promote this
principle. Studies of identical twins have shown that if one twin is gay, the
other has about a 55% of also being gay. Again, there is a very strong genetic
component at work.
Assume as a working assumption that 5% of adults are gay. A typical study
would involve:
The interview of perhaps 2,000 males, all of whom had separately raised
monozygotic twins.
The identification of about 100 gays.
Tracking down the other twin in each case, to determine their sexual
orientation.
Two possibilities are:
There is no genetic basis for sexual orientation. That is, a
statement by Parents and Friends of Ex-gays is correct: "To date, all
information and studies involving genetics have proven homosexuality to be
environmental, not genetic."
Then one would expect close to 5% of the second twins would
also be gay.
A homosexual orientation is totally caused by genes. One would then
expect that between 0 and 100% of the other twin would also be gay, depending
upon a property of the gene called its "penetrance."
This type of test has been performed by various groups of researchers. The
first such study found that 100% of the second twins were also gay. But this
study was based on a very small sample size; the results it turned out to be a
statistical fluke. Subsequent, larger, tests all reported that somewhat in
excess of 50% of the second twins are also gay. This indicates that genes play a
very significant role in determining sexual orientation. however, the number is
not 100%. This indicates that environment plays a role in determining sexual
orientation. It might be an event in the womb, or in early childhood. Other
studies, explained below, show that a person's eventual sexual orientation is
determined before they reach school age.
One problem with this and similar studies is that the researchers can ask
what a person's orientation is, but not necessarily get a valid answer; a gay
individual may be so firmly "in the closet" that they will not admit even
to a stranger what their actual orientation is. Also, most studies classify
subjects as either heterosexual or homosexual. A bisexual person might be
involved with persons of the opposite gender and consider themselves to be
heterosexual; their twin may also be bisexual but be involved with members of
the same gender, and identify themselves as homosexual. Another problem is that
identical twins share the same environment (their mother's womb) for the 9
months prior to birth. Thus, if there is a environmental factor which determines
sexual orientation, it might work on the fetus before birth. This series of
replicated studies proves beyond any doubt that at least male homosexuality is
largely determined before birth. As the
American Psychological Association's statement on homosexuality in
1994-JUL asserts: "Research suggests that the homosexual orientation is in
place very early in the life cycle, possibly even before birth..."
Kevin Schattenkirk, "Being gay - A choice? Debunking some popular views
on homosexuality," The Daily University of Washington, 1999, at:
http://archives.thedaily.washington.edu/ (No longer available online)
"Toward a new national discussion of homosexuality," Focus on the
Family, 1998-SEP-15, at:
http://www.family.org/cforum/
R. Blanchard, "Fraternal birth order and the maternal immune hypothesis
of male homosexuality," Hormones & Behavior, 2001, 40, Pages 105 to 114.
R. Blanchard & L. Elllis, "Birth weight, sexual orientation, and the sex
of preceding siblings," Journal of Biosocial Science, 2001, 33: Pages 451 to
467.
Dean Hamer et al, "A Linkage Between DNA Markers on the X Chromosome and
Male Sexual Orientation" Science 261 (1993-JUL-16): pp 321-27.
Mike Haley, "Straight Answers: Exposing the myths and facts about
homosexuality," Focus on the Family, Love Won Out series, (2000), Page 9.
Daniel R. Heimbach, "Notes for The Bible in the Moral War over
the Rejection of Homosexuality by the Military Services: A View from Inside the
Pentagon," PREMISE, Volume II, Number 7, 1995-AUG-27, Page 10. Online at:
http://capo.org/premise/95/august/
