"Born gay." The idea that homosexuality is genetic, or at least
biologically predetermined and unchangeable, has received a great amount
of media coverage presenting it as "new scientific fact." What is often
not known is that this "born gay" idea is not new, not proven, and
frequently contradicted by what the researchers actually said. At least as
far back as 1899, German researcher Magnus Hirschfeld regarded
homosexuality as congenital - meaning, "born that way" - and he asked for
legal equality based on this thinking.
Now, a century later, the idea that homosexual persons are born that
way has again received a great amount of media attention. As new research
studies were published, the popular press presented these as evidence that
people are "born gay" and that sexual orientation is therefore
unchangable. What has been quietly happening, though, is that the
"science" behind this idea is falling apart. Here we briefly examine the
three most cited studies, from Simon LeVay, Michael
Bailey & Richard Pillard, and Dean Hamer.
Simon LeVay and the INAH-3
"Time and again I have been described as someone who 'proved that
homosexuality is genetic' ... I did not."
Simon LeVay in The Sexual Brain, p. 122.
Simon LeVay, a neuroscientist, studied the brains from 41 corpses,
including 6 women, 19 homosexual men, and 16 men presumed to be
heterosexual. A small area of the brain, the INAH-3, was similar in size
in women and homosexual men, but larger in heterosexual men. He suggested
that this might be evidence for an actual structural difference in the
brains of gay men. There are, however, numerous problems with this
The points on the graph represent the size of INAH-3 in the
brains from corpses of 6 women (F), 16 men (M; presumably
heterosexual) and 19 homosexual men (HM)
- In comparing the size of the INAH-3, he presumed that the 16
"heterosexual" men were, in fact, heterosexual. Only two of them
had denied homosexual activities; for the rest, sexual histories
were not available. Thus, he was actually comparing homosexual men
with men of unknown sexual orientation! This, obviously, is a
major flaw in scientific method.
- The volume of the INAH-3 may not be a relevant measure:
- Scientists disagree on the most accurate way to measure the
INAH-3. LeVay measured the volume; other scientists claim it is
more accurate to measure the actual number of neurons.
Clarifying the potential problem, some have suggested that using
a volume method to project impact on sexual orientation may be
like trying to determine intelligence by a person's hat size.
- When different laboratories have measured the four areas of
the INAH (including INAH-3), their results conflicted. For
example, Swaab and Fliers (1985) found that the INAH-1 was
larger in men, while LeVay (1991) found no difference between
men and women. Allen et al (1989) found the INAH-2 to be larger
in men than in some women, while LeVay (1991) again found no
difference. See Byne (1994), page
The above problems aside, even the data from LeVay's study did not
prove that anyone was born gay. This is the case for at least two reasons:
- Both groups of men covered essentially the same range of sizes. One
could be gay (HM) with a small INAH-3 or with a large one. One could
also be in the "heterosexual" category (M) with either a small or large
INAH-3. Clearly, these men were not held to a sexual orientation by
their INAH-3 biology! As the data shows, the INAH-3 size of three of the
homosexual men puts them clearly in the "heterosexual" category (with
one having the second largest INAH-3!). If all you know about any of
LeVay's subjects is INAH-3 size, you could not accurately predict
whether they are heterosexual or homosexual, male or female.
- A study that showed a clear difference in INAH-3 sizes, would still
leave another question unanswered: are men gay because of a smaller
INAH-3, or was their INAH-3 smaller because of their homosexual actions,
thoughts, and/or feelings? It is known that the brain does change in
response to changes in behaviour and environment. For example, Newsweek
reported that "in people reading Braille after becoming blind, the area
of the brain controlling the reading finger grew larger." As well, in
male songbirds, "the brain area associated with mating is not only
larger than in the female, but varies according to the season"
(Newsweek, Feb. 24, 1992, p. 50).
Bailey & Pillard: Twins and Other Brothers
Bailey and Pillard studied pairs of brothers -- identical twins,
non-identical twins, other biological brothers, and adoptive brothers --
where at least one was gay. At first glance, their findings looked like a
pattern for homosexuality being genetically influenced. Identical twins
were both homosexual 52% of the time; non-identical twins, 22%; other
biological brothers, 9.2%; and adoptive brothers, 10.5%. A closer look
reveals significant problems with a "born gay" conclusion to this
- "In order for such a study to be meaningful, you'd have to look at
twins raised apart," says Anne Fausto Sterling, a biologist. The
brothers in this study were raised together in their families.
- All the results were different from what one would expect if
homosexuality was directly genetic:
- Because identical twin brothers share 100% of their genes overall,
we would expect that if one was homosexual, the other would also be
homosexual, 100% of the time. Instead, this study found that they were
both homosexual only 52% of the time.
- Although completely unrelated genetically, adoptive brothers were
more likely to both be gay than the biological brothers, who share
half their genes! This piece of data prompted the journal Science to
respond: "this . . . suggests that there is no genetic component, but
rather an environmental component shared in families" (Vol. 262
- If homosexuality were genetic, one would expect each number in the
column "Results from the B & P study" to be identical to the
corresponding number in the "Expectation if genetic" column. Each one
is significantly different!
Both are Homosexual:|
|Results from |
|Identical twin brothers
|Non-ident. twin brothers
|| 50 %
|| 50 %
|Other biological brothers
|| 50 %
|| 50 %
|| 9 %|
|| 0 %
|| 1-4 %
- Finally, Bailey & Pillard did not use a random sample. The men
in the study were recruited through advertisements in gay newspapers
Dean Hamer and the Xq28 Genetic Markers
Hamer studied 40 pairs of homosexual brothers, and reported that 33
pairs shared a set of five genetic markers. Reporting the story, Time
magazine's cover read "BORN GAY Science Finds a Genetic Link" (July 26,
1993). Hamer, however, was more cautious. He felt that it played "some
role" in a minority of 5 to 30% of gay men (The Science of Desire
by Dean Hamer and Peter Copeland. New York: Simon & Schuster, 1994.
Pages 145-146). This is a rather distant reality from finding the "gay
gene" and it left two critical questions: just how much influence was
"some role" thought to be, and what about the other 70 to 95%?
- Based on a simple genetic theory, one would expect 50%, or 20
pairs, to have the same markers. Why did 7 pairs of gay brothers not
share a set of genetic markers?
- Hamer did not check to see if the heterosexual brothers of the
homosexual men also had such a genetic marker. Thus, there was no
control group in this study. Here too, this obviously is a major flaw
in scientific method.
- Since that time, Science has reported that George Ebers, a researcher at the University of Western
Ontario, has attempted to duplicate the study but found "no evidence,
not even a trend," for the "genetic link." In the scientific world,
that is a big problem. More recently, another study by Rice et al. has
also stated that its results "do not support an X-linked gene
underlying male homosexuality."
Now even the gay and pro-gay press are acknowledging the
problems. In her 1996 book, Gender Shock, writer and
lesbian woman Phyllis Burke, quoting Dr. Paul Billings, an
internist and human geneticist, calls the born gay idea "a new
fish story." A gay publication, "The Guide," writes Hamer's story
under the title "Gene Scam?"
As well, Parents, Family and Friends of Lesbians and Gays
(PFLAG), one of the larger pro-gay organizations, explains that
there is no conclusive evidence that people are born gay in its
booklet "Why Ask Why? Addressing the Research on Homosexuality and
Born gay? Ironically, what the studies actually suggest is that
persons who experience same-sex attraction are not prisoners of
their biology. That's good news for same-gender-attracted people
who would rather pursue other options.
The media seized upon a study suggesting the
existence of a 'gay gene.' Now that it is unravelling, mum's the
The Guide, October 1995
References to Main Articles:
- LeVay, S. (1991). A difference in hypothalamic structure between
heterosexual and homosexual men. Science, 253, August, 1034-1037. Data
in chart from p. 1036.
- Bailey, J.M & Pillard, R.C. (1991). A genetic study of male
sexual orientation. Archives of General Psychiatry, 48, December,
- Hamer, D. et al. (1993). A linkage between DNA markers on the X
chromosome and male sexual orientation. Science, 261 16 July, 321-27.
- [Square brackets list which of the three above articles are
- Byne, William & Parsons, Bruce (1993). Human sexual
orientation: the biologic theories reappraised. Archives of General
Psychiatry, 50, March 1993, 228-237. [LeVay, Bailey & Pillard]
- Byne, William (1994). The biological evidence challenged.
Scientific American, May 1994, 50-55. [all three]
- Cole, Sherwood O. (1995). The biological basis of homosexuality: a
Christian assessment. Journal of Psychology and Theology, 23(2),
89-100. [all three]
- Dallas, Joe (1992). Born gay? Christianity Today, June 22, 20-23.
[LeVay, Bailey & Pillard]
- LeVay, Simon & Hamer, Dean H. (1994). Evidence for a
biological influence in male homosexuality. Scientific American, May
1994, 44-49. [LeVay, Hamer]
- Looy, Heather (1995). Born gay? a critical review of biological
research on homosexuality. Journal of Psychology and Christianity,
14(3), 197-214. [all three]
- Marshall, Eliot (1995). NIH's "Gay Gene" study questioned.
Science, 268, Jun 30 1995, 1841. [Discusses G.C. Eber's attempt at
replicating Hamer's work].
- Muir, J.G. (1996). Sexual orientation - born or bred? Journal of
Psychology and Christianity, 15(4), 313-321. [all three]
- PFLAG (1995). Why Ask Why? Addressing the Research on
Homosexuality and Biology. Privately published booklet. [all three]
- Rice, G. et al. (1999). Male Homosexuality: Absence of Linkage to
Microsatellite Markers at Xq28. Science, 284(5414), 665-667. [Hamer]