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Born This Way:
Homosexuality, Science, the
Dr. J. Alan Branch
Midwestern Baptist Theological Seminary
Lady Gaga
• No matter gay, straight or bi
• Lesbian, transgendered life
• I’m on the right track, baby
• I was born to survive
• No matter black, white, or beige
• Chola or orient made
• I’m on the right track baby
• I was born to be brave
Lady Gaga
• I’m beautiful in my way
• Cause God makes no mistakes
• I’m on the right track, baby
• I was born this way
Talking Points
• Homosexuality is not a trait like skin color.
• Correlation does not equal causation.
• No trait has been discovered which is both
necessary and sufficient for homosexuality.
• Predisposition doesn’t equal predetermination.
I. Prenatal Hormones
Troy Perry, MCC Founder
• One thing is certain about me: I feel I have
a total sense memory that predates my
birth by a good long time. It’s like being a
seedling soul in two parts, your mother’s
and your father’s genes. I have an
awareness of having been a seedling – a
physical presence in my father’s sperm and
in my mother’s ovum before they were
• Troy Perry, The Lord is My Shepherd and He Knows I’m Gay (Los
Angeles: Nash Publishing, 1972), 10.
A. Prenatal Hormones Theory
• Hormones drive sexual development.
• Homosexuals got the correct gender-specific hormones
during genital development.
• Homosexuals got the discordant hormone for their sex
during brain development. (Boys got the girls’
hormones and girls got the boys’ hormones.)
B. Often Based on Animal Research
• Animals act instinctively; humans are volitional.
C. Disorders of Sexual Development Only
Show Weak to Possibly Moderate Support
• No ethical way to perform experiments on humans to
prove the theory.
• Disorders of Sexual Development provide “natural”
• Congenital Adrenal Hyperplasia (CAH): Body produces
too much androgen and girls can develop genitalia with
male characteristics.
C. Disorders of Sexual Development Only
Show Weak to Possibly Moderate Support
• Large majority of girls with CAH self-identify as
• A higher percentage self-identify as homosexual than in
the normal population.
• Hard to disentangle genetic influence from social
experience of growing up with a DSD.
• Does not prove that prenatal hormones explain the
development of a homosexual identification in most
II. Do Homosexuals Have
Different Brain Structures
Than Heterosexuals?
A. Theory Stated
• Same-Sex attraction is caused by men having
brain structures more similar to the average
woman and women having brain structures more
similar to the average man.
B. Simon LeVay, 1991
• Neuroanatomist with the Salk
institute; later with the Institute
of Gay and Lesbian Education.
• Examined the interstitial
nucleus of the anterior
hypothalamus (INAH): four cell
groups known as INAH 1, 2, 3,
and 4.
Photo of INAH 3 from 2008 Study
B. Simon LeVay, 1991
• 41 cadavers, LeVay identified 19 of
cadavers as homosexual males
(including one bisexual);16 as
heterosexual men; 6 as heterosexual
• He claimed the INAH 3 cell group
was more than twice as large in
heterosexual men than in women
and homosexual men.
C. Response and Critique
• LeVay’s own data
demonstrates a
weakness in the
C. Response and Critique
• Some of the homosexual men had an INAH 3 similar in
size to the majority of heterosexuals. A particular INAH
3 size is not necessary to cause homosexuality.
• Some of the heterosexual men had an INAH 3 similar in
size to the majority of homosexuals. A particular INAH
3 size is not sufficient to cause homosexuality.
C. Response and Critique
• William Byne, director of the Neuroanatomy and
Morphometrics Laboratory at the Icahn School of
Medicine at Mount Sinai 2001.
• No difference in number of neurons, but they seem to
be packed more tightly in homosexual males.
C. Response and Critique
• “Based on the results of the present study as well
as those of LeVay, sexual orientation cannot be
reliably predicted on the basis of INAH3 volume
• Byne, et al, “The Interstitial Nuclei of the Human Anterior Hypothalamus,”
2001, 91.
C. Response and Critique
•Since 1991, no clear replication of
LeVay’s results.
C. Response and Critique
• Generally, men have a higher
percentage of white matter,
and women a higher
percentage of gray matter.
• No difference discovered here
for homosexuals
III. What Can We Learn
From Twin Studies?
A. Bailey and Pillard (1991)
• Identical and Non-Identical Male Twins
• Found that if one identical twin is homosexual, there is
a 52% chance the other identical twin will be
homosexual as well.
• But between non-identical twins, there was only a 22%
correspondence for homosexuality.
• We now know this data is inaccurate.
B. Bailey, Dunne, and Martin – 2000
• Shows 1991 data was inaccurate.
• Used a much larger sample of Australian twins. Only
20% correspondence for Homosexuality among
identical male twins.
• 24% correspondence for homosexuality among identical
female twins.
• 2010 Swedish Twin Study: Similar Results.
C. Response
• If one identical twin is homosexual, the chances the cotwin will also be homosexual is much higher than in the
average population.
• But the vast majority of co-twins are not homosexual.
• This higher occurrence demonstrates the plausibility of
some genetic factor exhibiting a low level of influence.
C. Response
• Actually strongly questions the “Born This Way”
• If homosexuality were completely genetic, there
would be 100% correspondence.
• Homosexuality is not a trait like hair or skin
IV. Has Science
Discovered a Gay Gene?
A. Theory Stated
• People are homosexual because of a gene or genes
that causes homosexuality in manner similar to
the way genes code for skin color or eye color.
B. Dean Hamer, 1993
• Director of the Gene Structure and
Regulation section at the National
Cancer Institute.
• A sample of 40 pairs of
homosexual brothers.
• Claimed 33 of 40 pairs of
homosexual brothers had coinherited genetic information in
the X-chromosome in a region
called “Xq28”.
B. Dean Hamer, 1993
• Hamer did not claim to find a gay
gene, he claimed to find a region
on a chromosome where a “gay
gene” might exist.
• There are lots of genes in the Xq28
• 1995; could find nothing for
females. Some heterosexual males
shared something at Xq28.
B. Dean Hamer, 1993
• “Even within the selected
population that was studied, the
Xq28 region was neither necessary
nor sufficient for homosexual
orientation.” Hamer’s team, 1995
C. Sanders, Bailey, Et Al 2015
• Sanders with the University of Chicago; Bailey is the
same guy from Twin Studies
• 409 pairs of gay brothers from 384 families
• Two regions of linkage identified:
• One area on Chromosome 8 (8q12) and Xq28
• Claim to have replicated Hamer’s data
D. Response and Critique
• Using Genetic Linkage Analysis: Points to a Region and
not specific base-pairs in the DNA.
• Neither Hamer nor Sanders/Bailey were claiming to
have found a specific gene.
• In both cases, the genetic sequence at Xq28 was
different among each of the pairs of brothers.
• What was common was the location of the sequences.
D. Response and Critique
• Sanders and Bailey admit their results have weak
predictive power.
• “Regarding any scenario that research in this area will
result in a prenatal genetic test for homosexuality, the
small magnitude of effects suggested herein are
inconsistent with a test that those motivated to
influence their children’s sexual orientation would find
• Admit data on Xq28 actually just below threshold for
D. Response and Critique
• 2012 study presented at the American Society of Human
Genetics by the 23andMe database. (Private Company)
• More modern and precise, genome-wide association
• 23,000 individuals.
• No linkages reaching genome-wide significance for
same-sex sexual identity for males or females.
D. Response and Critique
• No one has discovered a “gay gene.”
• Some regions of possible interest for some males in
particular samples, but no areas of interest ever
discovered for females.
V. Does Having More Older
Brothers Make Someone Gay?
A. Theory Stated
• Each older brother increases the odds of
homosexuality by 33%.
• Theory claims 1 out of 7 homosexual men can
attribute same-sex attraction to the fraternal birth
order effect.
B. Response
• Problems with the source of the samples.
• 2006 study of entire population of Denmark found no
substantial birth order effect.
• Half or more of all homosexual men have zero older
• Contrary to popular opinion, scientific research
has not found a “gay gene.”
There is no conclusive evidence that homosexuals
have a substantially different brain structure than
• A survey of modern scientific research demonstrates
there are some factors with a low level of influence that
correlate with a higher incidence of homosexuality
among some populations.
• However, no biological or genetic factors have yet been
discovered that cause homosexuality.
• Correlation does not equal causation.
Linda Diamond of the University of
Utah, Oct. 27, 2013
• “I feel as a community, the queers have got to stop
saying, ‘Please help us. We’re born this way and we can’t
change’ as an argument for legal standing. I don’t think
we need that argument, and that argument is going to
bite us in the [rear end], because we know that there’s
enough data out there, that the other side is aware of it
as much as we are aware of it.”
Born This Way:
Homosexuality, Science, the
Dr. J. Alan Branch
Midwestern Baptist Theological Seminary