
ON JULY 15, 1993, National Public Radio (NPR) made a dramatic announcement on stations
across the country: Was a team of scientists
at the National Institutes of Health on the trail of a
gene that causes homosexuality? Their report would be
published the next day in Science, one of the two most
prestigious scientific research journals in the
world.(1)
The discussion that followed explained for the
listening public the implications of these findings for
social attitudes toward homosexuality and for public policy
concerning it. Science was on the verge of proving what
many had long argued: that homosexuality is innate,
genetic and therefore unchangeablea normal and
commonplace variant of human nature. In the light of these
findings, surely only the bigoted or ignorant could condemn it
in any way.
Shortly after the announcement, amidst a
well-orchestrated blizzard of press discussions, there ensued
the watershed legal battle over "Proposition 2" in
Colorado. (This popularly enacted legislation precluded
making sexual orientation the basis of "privileged class"
minority status, a status conferred previously only on the basis
of immutable factors such as race.)
Among the many crucial issues raised by the
legislation was the question as to whether homosexuality
was indeed normal, innate and unchangeable. One
prominent researcher testified to the court, "I am 99.5%
certain that homosexuality is genetic." But this personal
opinion was widely misunderstood as "homosexuality is
99.5% genetic," implying that research had demonstrated
this. Certainly, that was the message promulgated by
NPR's report on the recent research, and by all the
discussions that followed. In a few weeks,
Newsweek would emblazon across its cover the phrase that would stick in the
public mind as the final truth about homosexuality: "Gay Gene?"
Of course, just near the end of the NPR
discussion, certain necessary caveats were fleetingly added. But
only an expert knew what they meant--that the research
actually showed nothing whatever in the way of what was
being discussed. The vast majority of listeners would think
that homosexuality had been all but conclusively proven to
be "genetic." But the real question is whether or not there
is such a "gay gene."
In fact, there is not, and the research being
promoted as proving that there is provides no supporting
evidence. How can this be? In order to understand what is
really going on, one needs to understand some little-known
features of the emerging study of behavioral
genetics (much subtler than the genetics of simple, "Mendelian"
traits such as eye color).
When it comes to questions of the genetics of
any behavior--homosexuality included--all of the
following statements are likely to be at least roughly true:
The scientific distinctions that make these
seeming contradictions perfectly reasonable and consistent
seem completely misunderstood by the media who report on them.
FOR EXAMPLE, in response to the "gay gene" research, the
Wall Street Journal headlined their report (which
appeared the next day), "Research Points Toward
a Gay Gene."(2) A subheading of the
Journal article stated, "Normal Variation"--leaving the casual reader with
the impression that the research led to this conclusion. It
did not, nor could it have. The subhead alluded to
nothing more than the chief researcher's personal,
unsubstantiated opinion that homosexuality, as he put it, "is a
normal variant of human behavior." Even the
New York Times, in its more moderate front-page article, "Report
Suggests Homosexuality is Linked to Genes," noted that other
researchers warned against over-interpreting the work,
"or taking it to mean anything as simplistic as that the
'gay gene' had been found."
At end of the Wall Street Journal article, at the
bottom of the last paragraph on the last page deep within
the paper, a prominent geneticist was quoted for his
reactions to the research. He observed that "the
gene...may be involved in something other than sexual behavior.
For example, it may be that the supposed gene is only
'associated' with homosexuality, rather than a 'cause' of
it."
This rather cryptic comment would be most
difficult to understand without the needed scientific
background. Yet it is the most critical distinction in the
entire article; indeed, it renders the findings almost
entirely worthless. Why bury and fail to explain what it
means? Perhaps the motives were innocent, but in fact, the
belief that homosexuality is "biological" or "genetic"
causes people to develop more positive attitudes toward it.
They need not have the foggiest understanding of what
"biological" or "genetic" really mean in order to change
their view:
And:
To the uninitiated, a positive finding
("correlation" or "association" of a genetic structure with a
behavioral trait) is taken to mean that the trait "is genetic"--that
is, inherited.
In fact, it means absolutely nothing of the sort, and
it should be emphasized that there is virtually no human
trait without innumerable such correlations. We will see
shortly just how this is can be so. The most important
take-home messages will be these:
(1) All the research that has been done on
homosexuality has been selectively trumpeted through the
press in carefully crafted form in order to shape public
opinion--hence public policy--in predictable ways. The
research itself means almost nothing.
(2) The research projects that would
truly mean something are scarcely being done because they would all
explicitly or tacitly lead to but one end highly
undesirable to activists: a method or methods for preventing
homosexuality or changing it with ever-increasing efficacy;
and to one conclusion: homosexuality per se is not inherited.
(3) Most of the research has been hastily and
often sloppily done--but this point is a distraction. Even
were it superb, the findings would still mean almost nothing.
(4) To whatever extent this research has been
good enough to generate valid conclusions at all, these
conclusions are precisely the opposite of what is claimed in
the press.
BEFORE WE TALK about specifics, here is what serious scientists think
about the recent behavior-caused-by-genes research. From Science,
1994:
A scientist at Washington University School of
Medicine calculated what would be required for such a
replication. He:
Nothing even remotely close to this has been done
with respect to homosexuality.
Using arguable-at-best methods, two American
activists recently published studies showing that if one of
a pair of identical twins is homosexual, the odds that
the other one is, too, are less than 50% (the study
examined a few dozens of pairs). On this basis, they argue that
"homosexuality is genetic." British researchers
generated comparable results in a similar study. Their
conclusion? The surprisingly low odds that both twins
were homosexual:
TWO COLUMBIA UNIVERSITY researchers (who have published the
most comprehensive research summary on the subject to date) note the
unexpectedly:
Two other genetics researchers (one heads one of
the largest genetics departments in the country, the other
is at Harvard) comment:
The author of the lead article on genes and
behavior in a special issue of Science notes:
The director of the Center for Developmental and
Health Genetics at Pennsylvania State University comments:
(Note the term "heritability;" we will be returning to it
in detail as it lies at the heart of much confusion).
With regard to the work announced by NPR,
genetics researchers from Yale, Columbia and Louisiana
State Universities noted that:
The results are not consistent with any genetic model....neither of these differences
[between homosexuality in maternal versus paternal
uncles or cousins] is statistically significant....small
sample sizes make these data compatible with a
range of...hypotheses.
[T]he...data...present no consistent support for
the...results.(14)
By contrast to their public policy statements, the
researchers responded carefully as follows:
IGNORING POSSIBLE FLAWS in the research, have the researchers
actually pointed to this more modest claim with any degree of certainty?
In fact, they have
not--as they themselves acknowledge, but in language that
will surely evade general understanding--and that will
continue to be avoided by the press:
English translation: "It is not possible to know what
the findings mean, if anything, since sexual orientation
cannot possibly be inherited the way eye-color is." Thus,
to their fellow scientists, the researchers properly
acknowledge what every serious researcher knows, but the
public does not.
English translation: "You're more likely to become
gay growing up in Manhattan than in Utah among
Mormons and Christian fundamentalists, even if everything else
is the same, including genes."
Unfortunately, anyone who is so disposed can
readily offer the public partial truths which are seriously
misleading. This is so only in part because of an easily led
or poorly educated press. The major reason is really that
the ideas being cooked beyond recognition once they
leave the labs are inherently complex, even if originally
formulated and presented properly. There are no "lite,"
sound-bite versions of behavioral genetics that are not
fundamentally in error in one way or another.
Nonetheless, if one grasps at least some of the
basics, in simple form, it will be possible to see exactly why
the current research into homosexuality means so
little--and will continue to mean little even should the quality of
the research methods improve--so long as it remains
driven by political, rather than scientific objectives.
THERE ARE REALLY only two major principles that need to be carefully
assimilated in order to see through public relations distortions to the actual
meaning of recent research. They are as follows:
Heritability studies can be done on almost any
human trait--physical, behavioral, emotional, etc.--and
will show positive results. That is, almost every human
characteristic you can think of is in significant measure
heritable (thus discussing it is "trivial"). But few human
behavioral traits are directly inherited the way simple
physiological traits are (e.g., eye color). Inherited
means "determined directly by genes," with little or no way of
changing the trait by choice, or by preventing it, or by
modifying the environment in which the trait has emerged (or
is more likely to emerge).
Here is a simple hypothetical example, but it is
100% plausible. It tracks the kinds of studies that have
been done with innumerable other traits, including
homosexuality. (But only in the area of homosexuality has the
meaning of such studies been so badly distorted).
Suppose that for political reasons you want to
demonstrate that there is a "basketball gene" that
"makes" people become basketball players ("BBPs"). (Please
suspend your immediate, correct understanding that the
idea is absurd.) To make your case you would use the
same methods as with homosexuality. These methods fall
into three categories, and represent important forms of
preliminary research when investigating any trait: (1)
twin studies; (2) brain dissections; (3) gene "linkage" studies.
Twin Studies
The basic idea in twin studies is to show that
the more genetically similar are two people, the more likely
it is that they will share the trait you are studying. So,
you create a study set of pairs of people, divided into
categories according to how genetically similar they are, as follows:
Identical Twins -- 100%
Fraternal Twins -- 50%
Non-Twin Siblings -- 50%
Unrelated People -- <5%
The most similar are identical twins, the next most
similar are fraternal twins (who are on average as different
as non-twin brothers or sisters, but no more so), the
least similar are unrelated people.
Then you identify those pairs of twins in which
at least one is a BBP. It will not be difficult to show that
if one such identical twin is a BBP, his brother (or her
sister) more frequently will be, too, than would a
non-identical twin or a non-twin sibling or a non-sibling.
You would create groups of such different kinds of pairs
to make the comparison in a large number of cases.
(One set of identical twin pairs, one set of non-identical
twin pairs, one set of non-twin siblings, and so on.)
From the "concordance rate" in each set (the
percentage of pairs in each set in which either both are
BBPs or both are not. Pairs in which one was and the other
was not would be called "discordant for BBP") you
would calculate a "heritability" rate. (Perhaps you have an
armchair guess as to how many identical twin-pairs
either both play or both do not play basketball. Probably a
good deal more than half, the concordance rate for
homosexuality in such twin-pairs.)
You respond to the reporter from Sports
Illustrations that, "Our research demonstrates that BBP is very
strongly heritable," and you would be right. But the article
that comes out that month reads something slightly
different, but completely wrong. "...Recent research shows that
BBP is probably inherited. A number of outside
researchers examined the work and found it substantially
accurate and well-performed. They cautioned against arriving
at hasty conclusions, however." No one notices the difference.
Brain Dissections
Second, your colleagues perform a series of
autopsies on the brains of some dead people who appear to
have been BBPs. (Old jerseys, high-top sneakers and
Knicks ticket-stubs were found among their possessions, for
example.) They do the same with a group of dead
non-players (no sneakers, jerseys or tickets.) They report that,
on average, "certain parts of the brain long thought to
be involved with BBP are much larger in the group of
BBPs than in the controls." Certain nationally renowned
newspapers in the Northeast pick up on the story and
editorialize, "It will be very difficult for anyone except
poorly educated yokels who believe in Santa Claus, the
Tooth-Fairy and God to argue that BBP is not inborn. For
not only has it been proven to run in families, even the
brains of basketball players are
different."(18)
In a pretense of balance, some of these papers
interview diehard believers in the old view--yokels who
still think that one must decide to play basketball, and play
it for a long time, before you really can be considered
"a BBP." One of them is quoted as claiming that, "maybe
if you do something long enough your brain changes as
you get better at it, and that part of the brain gets
bigger." (Remarkably enough, this surmise seems obvious to
the old-time believer.) The reporter does not merely
report the comment, however, he also hints that it is
especially idiotic--typical of diehards and yokels--since
everyone knows the brain does not change.
Of course, you yourself are well aware that
among neuroscientists it is extremely old news that the brain
indeed changes, quite dramatically, in just the way the
old diehard guessed: those parts responsible for an
activity get much bigger over time (and there are definitely
parts that are more utilized in BBP). You will not lie about it
if asked (since you will not be), but neither will you go
out of your way to confirm the truth.
Gene "Linkage" Studies
Now for the coup de grace. You find a couple of
families of BBPs and compare them to some families of
non-BBPs. You have a hunch that of innumerable genes
of every imaginable sort likely to be "associated" or
"linked" to BBP (you never use the word "causing" because you
do not need to--no one knows the difference), there are
some genes on, say, the X-Chromosome. After a few false
starts, sure enough, you find what you are looking for:
among the BBP families one particular chromosomal
variant (cluster of genes) is more commonly found (though
not always) than among the non-players.
Now, sympathizers at National People's Radio
were long ago quietly informed of your research, since
they want people to come around to certain beliefs, too. So,
as soon as your work hits the press, they are on the air:
"Researchers are hot on the trail of the 'Basketball Gene!'
In an article to be published tomorrow in Sports
Science..." Learned-sounding commentators pontificate in soft,
accentless, perfectly articulated and faintly
condescending tones about the enormous public policy implications
of this superb piece of science-in-the-service-of-humankind.
Two weeks later, there it is again, at a jaunty angle
across the cover of the major national newsweekly:
"Basketball Gene."
NOW WHAT IS wrong with this scenario? It is simple: of course BBP is
heritable ("has a non-zero heritability" to use the words of homosexuality
researchers). That is because many physiological
traits--muscle strength, speed, agility, reflex speed, height,
etc.--are themselves directly inherited, and they make it
more or less likely that one can, and will want to, and will
successfully, and will therefore continue to want to, and
will in fact continue to, play basketball. In short, because
of intermediate inherited traits
associated with BBP (none of which
are BBP), it shows significant
heritability. (The genetic
association, of course, is in no way necessary or
predetermined, and is highly culturally conditioned:
there were no BBPs at all in, say, ancient Greece, yet the
same genes were there.)
BBP also shows a strong biological representation
in the brain, both at birth (e.g., nervous system factors
contributing to reflex speed) and especially later (e.g.,
the parts of the cortex that are cultivated and become
responsible for the movements of basketball, as in the huge
increases in finger-related brain tissue among blind
people who learn Braille).
And the specific genes that run in families that
are responsible for height, athleticism, etc. can surely be
found and they will be statistically linked to BBP. And if
one identical twin decides to play basketball, the
unusually strong emotional bond between such siblings will
make it even more likely that his twin will, too. (The fact
of their genetic identity, not their specific genes, are here
influencing an outcome above and beyond the indirect
contributions from any specific genes.)
The basic problem is this: BBP is "influenced"
(made more or less an easy and enjoyable thing to do) by
the presence or absence of other associated traits. For
BBP we can readily guess what they are and so
immediately see that the "genetic" component of BBP has nothing
to do with the game itself but with these associated
(facilitating) traits. What are these traits? Height,
athleticism, bone structure, reflexes, muscle refresh rate, and so
on. So evident are the specifics of this association that no
serious researcher will waste his time looking into the
genetics of BBP proper; he will concentrate on the
obvious intermediate traits--height, athleticism and so on.
The same is true for homosexuality, except (a)
the more important, intermediate traits with which it is
associated are mostly unknown and suspected ones are
harder to confirm, and (b) the research agenda is being
distorted by the political requirement that no such associated
traits be discovered and that homosexuality be falsely
presented as directly inherited.
Research into merely heritable traits is useful only
in generating hypotheses about what the directly
inherited traits might be. Here is what this means: Let us
imagine that it was not immediately evident to us that the
heritable aspects of BBP were intermediate traits such
as height. A good researcher would not be at all tempted
to conclude from the studies we described that BBP
itself was inherited. He would conclude however that,
indeed, there must be some inherited traits that facilitate
BBP, and it would be these as-yet-unknown traits that
were producing the "non-zero heritability" results. If he
could identify the traits correctly, he would find that the
heritability results, when he redirected his genetics research,
would increase dramatically.
In other words, studying the genetics of BBP is
really a crude way of unwittingly studying the genetics of
height and athleticism, etc. If he selects his population on
the basis of the indirect trait (BBP), when it is other
traits that are really inherited, the researcher's results will
be "fuzzed up" by the inevitable proportion of BBP's
who lack these traits, or have them in lesser degree (e.g., a
small number of shortish BBPs). But if he correctly
identifies the traits in question, his next round of studies will
"divide the herd" more efficiently, corralling his subjects
not by BBP (or "sexual orientation"), but by height. Of
course, there will be more BBPs among the tall subjects
than among the short, but that is incidental. He will seek
out other tall people who are not BBPs, and in his new
study, the heritability factor (height) will be even more
concentrated.
How might he guess at what the most important
traits are, and then try to confirm his guess, so he could
investigate the genetics of these traits? Very simply: he
looks, does the best he can to name what he sees, and tries
not to run afoul of the currently fashionable taboos
enforced by the thought-police! He will probably have no
trouble studying height, but he might run into difficulties
should he suspect that athleticism (or even height) has a
racial association. (More people of Nordic stock, being
taller, become basketball players than do people of
Appenzeller Swiss stock, being short. Perhaps other such
groupings might occur to a researcher.)
In the case of homosexuality, the
inherited traits that are more common among homosexuals (and that
produce "non-zero heritability" in studies) might include
such qualities as greater than average tendency to anxiety,
shyness, sensitivity, intelligence, aesthetic abilities and so
on. (Of course, these traits may themselves be further
reducible to a variety of mutually influencing, associated
genetic and non-genetic factors.) The brain changes
that are more prevalent among homosexuals, the tendency
of homosexuality to run in families (and to vary with
degree of genetic similarity within families) and the presence
of associated chromosomal markings are all certainly due
to as yet unresearched and therefore not-yet-identified
intermediate traits. There is no evidence that
homosexuality itself is inherited.
Like height and BBP, these traits--intelligence,
say, or anxiety--are surely widely distributed in the
population at large and densely present therefore in groups
that are properly selected to have them. If researchers had
divided their populations by shyness or aesthetic
sensibility, and ignored the homosexual/non-homosexual
division, they might well have found even stronger
chromosomal linkages as well as brain changes and twin
concordance rates.
Here, then is a final summary, in the form of a dialogue.
Isn't homosexuality heritable?
Yes, significantly.
So it is inherited?
No, it is not.
I'm confused. Isn't there is a "genetic component" to
homosexuality?
Yes, but "component" is just a loose way of
indicating genetic associations and linkages. This will not
make sense unless you understand what, and how little,
"linkage" and "association" really means.
What about all the evidence that shows that
homosexuality "is genetic"?
There is not any, and none of the research itself
claims there is; only the press and, sadly, certain researchers
do--when speaking in sound bites to the public.
But isn't homosexuality "biologically in the brain"?
Of course it is. So is just about everything else.
I'll
So doesn't that mean that homosexuality is "innate"?
No more than prayer is. The brain changes with
use or nonuse as much as muscles do--a good deal more,
in fact. We just do not usually see it happening.
But doesn't homosexuality run in families?
Yes.
So you get it from your parents, right?
You get viruses from your parents, too, and some
bad habits. Not everything that is familial is innate or genetic.
But it just seems to make sense. From the people I
know there's a type--it's got to be inherited--that runs in
families and a lot of these people are gay, right?
That is what associated traits are--but what
exactly is the associated trait--or traits--you are detecting?
If there is one thing the research confirms, it is that it is
not "gayness" itself. That is why these traits are sometimes
in evidence at a very early age, long before sexuality is shaped.
So what are these traits?
An important question, indeed. Science is being
seriously obstructed in its effort to answer that question.
If we were allowed--encouraged--to answer it, we would soon develop better ideas on what homosexuality is
and how to change, or better, prevent it. We would know
who was at greater risk for becoming homosexual and
what environments--family or societal--foster it. As
one prominent gay activist researcher implied, all
genetic things being equal, it is a whole lot easier to become
"gay" in New York than in Utah. So who do you think
would benefit most from that kind of research?
Well, what traits do you guess are "associated," as you
put it, with homosexuality?
May I speculate, perhaps wildly? That is how
scientific hypotheses are first generated. The important
thing is not to avoid ideas that prove wrong, just not to cling
to them if they do.
Okay, go ahead, speculate.
Intelligence, anxiety, sensitivity, aesthetic
abilities, taste. You know, all the stereotypes.
But where do these traits come from? Aren't they
inherited?
We do not know yet. Some may be. Or rather, we
do not know how much is inherited, and which elements
are direct and which merely further associated and linked
with other yet more fundamental traits. But you are
getting the picture. That is how the research ought to proceed.
It
Jeffrey B. Satinover, M.D. has practiced psychoanalysis for
more than nineteen years, and psychiatry for more than ten. He is
a former Fellow in Psychiatry and Child Psychiatry at Yale
University, a past president of the C.G. Jung Foundation, and
a former William James Lecturer in Psychology and Religion
at Harvard University. He holds degrees from MIT, the
University of Texas, and Harvard University. He is the author of
Homosexuality and the Politics of Truth (Baker Books, 1996).
Endnotes:
(1) D. H. Hamer et al, "A Linkage Between DNA Markers on
the X-chromosome and Male Sexual
Orientation," Science (1993), 261, no. 5119, pp. 32127.
(2) "Research Points Toward
a Gay Gene," Wall Street
Journal, 16 July 1993.
(3) A lower score on this scale means a less negative attitude
toward homosexuality.
(4) Piskur and Degelman, "Attitudes Toward Homosexuals,"
Psychological Reports 71 (1992); my emphasis, pp. 1219-25 (part 2 of 3). See
also K. E. Ernulf, "Cross-National Analysis."
(5) K. E. Ernulf, S. M. Innala, and F. L. Whitam, "Biological
Explanation, Psychological Explanation, and Tolerance of
Homosexuals: A Cross-National Analysis of Beliefs and Attitudes,"
Psychological Reports 65 (1989), pp. 100310 (1
of 3).
(6) Mann C. Genes and behavior.
Science 264:1687 (1994).
(7) None of the studies of the genetics of homosexuality (all
of which are initial; none are replicatory) have come even remotely
close to studying this many subjects.
(8) Mann C. op. cit. p. 1688.
(9) King, M and McDonald, E. Homosexuals who are
twins: a study of 46 probands. British Journal of Psychiatry 160:407-409 (1992)
(10) Byne W and Parsons B. Human sexual orientation: the
biologic theories reappraised. Archives of General
Psychiatry. 50, 3:230 (1993).
(11) Quoted by Horgan, J., Scientific
American: Eugenics Revisited. June 1993, p. 123.
(12) Billings, P. and Beckwith, J.
Technology Review, July, 1993. p. 60.
(13) Mann C. op. cit. pp. 1686-1689.
(14) Risch N., Squires-Wheeler E., and Bronya J.B.K., "Male
Sexual Orientation and Genetic Evidence,"
Science 262 (1993), pp. 2063-65.
(15) Hamer DH et al. Response to Risch N et al.
ibid. p. 2065
(16) Hamer DH et al. Response to Risch N
et al. loc. cit.
(17) Mann C., op. cit. p. 1687.
(18) Readers may recall Simon LeVay's much touted discovery
that the certain parts of the brains of (supposedly) homosexual men
were larger than among (supposedly) heterosexual men. But even if
the research is valid--its quality has been strongly criticized--the
discovery of brain differences per se is on a par with the discovery that
athletes have bigger muscles than non-athletes. For though a genetic
tendency toward larger muscles may make it easier to--and
therefore more likely that one will--become an athlete, becoming an
athlete will certainly give one bigger muscles.
When this particular critique was raised, the press quickly
took its accustomed potshot at the usual "poorly educated and easily
led" religious groups for the suggestion's politically incorrect
implications: "Some religious fundamentalists even suggested that homosexual
activity somehow could have caused the structural differences [that
LeVay claimed to have discovered]."
But as the editor of Nature--an equally prestigious publication--
wrote, commenting on the LeVay research: "Plainly, the neural
correlates of genetically determined gender are plastic at a sufficiently
early stage....Plastic structures in the hypothalamus allowing the
consequences of early sexual arousal to be made permanent might suit
[those who claim an environmental origin to homosexuality] well."
This editor is not, to anyone's knowledge, a religious fundamentalist.
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Love In Action
In this age, in this country, public sentiment is everything.
With it, nothing can fail; against it, nothing can
succeed. Whoever molds public sentiment goes deeper than he who enacts statutes,
or pronounces judicial decisions.
--Abraham LincolnThe Gay Gene?
by Jeffrey Satinover, M.D.
1. Such and such a behavior "is genetic";
2. There are no genes that produce the behavior;
3. The genes associated with the behavior are
found on such and such a chromosome;
4. The behavior is significantly heritable;
5. The behavior is not inherited.
105 volunteer[s]...were exposed to one of three...conditions....[T]he experimental
group read a summary...emphasizing a biological component of homosexual orientation....[O]ne
control group read a summary...focusing on the absence of hormonal differences between
homosexual and heterosexual men. [A]nother control
group w[as] not exposed to either article....As
predicted, subjects in the experimental group had
significantly lower(3) scores [more positive attitudes
toward homosexuals] than subjects in the control
groups.(4)
Analysis indicated that subjects who believed
that homosexuals are "born that way" held
significantly more positive attitudes toward homosexuals
than subjects who believed that homosexuals
"choose to be that way" and/or "learn to be that
way."(5)
WHAT WAS ACTUALLY going in the study the media was trumpeting? Dean Hamer and his
colleagues had performed a kind of behavioral genetics study now becoming widespread--the
so-called "linkage study." Researchers identify a behavioral trait
that runs in a family and then look to see whether there is
a chromosomal variant in the genetic material of that
family, and if that variant is more frequent in the family
members who have the trait.
Time and time again, scientists have claimed
that particular genes or chromosomal regions are
associated with behavioral traits, only to withdraw
their findings when they were not replicated.
"Unfortunately," says Yale's [Dr. Joel] Gelernter, "it's
hard to come up with many" findings linking
specific genes to complex human behaviors that have
been replicated. "...All were announced with great
fanfare; all were greeted unskeptically in the
popular press; all are now in disrepute."(6)
...projected that if the trait [in question] was
50% heritable...detecting [just] one of [its] genes
would require studying 175 families--that is, almost 2000
people.(7) Replicati[on] would require studying 781 families--another 8000 people....
[E]ach additional gene (for a polygenic trait),
researchers would need...the whole business again.
"Suddenly you're talking about tens of thousands of
people and years of work and millions of
dollars."(8)
...confirmed that genetic factors are
insufficient explanation for the development of sexual
orientation.(9)
...large proportion of monozygotic twins who [did not share]
homosexuality despite sharing not
only their genes but also their prenatal and familial
environments.(10) The...[50% odds]...for homosexuality among the identical twins could be
entirely accounted for by the increased similarity of
their developmental experiences. In our opinion,
the major finding of that study is that 48 percent
of identical twins who were reared together [and where at least one was homosexual] were
discordant for sexual orientation.(11)
...recent studies seeking a genetic basis for homosexuality suggest that
...we may be in for a
new molecular phrenology, rather than true
scientific progress and insight into behavior.
While the authors interpreted their findings as
evidence for a genetic basis for homosexuality,
we think that the data in fact provide strong
evidence for the influence of the environment.(12)
...the growing understanding that the
interaction of genes and environment is much more
complicated than the simple "violence genes" and
"intelligence genes" touted in the popular press.
Indeed, renewed appreciation of environmental factors is
one of the chief effects of the increased belief in
genetics' effects on behavior [my emphasis]. The same
data that show the effects of genes also point to
the enormous influence of non-genetic factors.(13)
Research into heritability is the best
demonstration I know of the importance of the environment.
Much of the discussion of this finding [of
a purported gene locus for homosexuality] has focused on its social and political ramifications.
[But] inconsistencies...suggest that this finding
should be interpreted cautiously....
We did not say that [the chromosome segment under study] "underlies" sexuality, only that it
contributes to it in some families. Nor have we
said that [it] represents a "major" gene, only that
its influence is statistically detectable in the
population that we studied.(15)
...the question of the appropriate significance
level to apply to a non-Mendelian trait such as
sexual orientation is problematic.(16)
Complex behavioral traits are the product of
multiple genetic and environmental antecedents, with 'environment'
meaning not only the social
environment but also such factors as the 'flux of
hormones during development, whether you were lying on your right or
left side in the womb and
a whole parade of other things'...the
relationships among genes and environment probably have
a somewhat different effect on someone in Salt
lake City than if that person were growing up in
New York City.(17)
1. Heritable does not mean
inherited.
2. Meaningful genetics research identifies and
then focuses on traits that are directly
inherited. One prominent genetics researcher (discussing a matter unrelated
to homosexuality, but equally frustrated with the bad
science reporting) flatly calls the question of
heritability "trivial."
Heritable Does Not Mean Inherited
Pair Type -- Degree of
Similarity (% same genes)
Meaningful Genetics Research Identifies and Focuses on Traits
That Are Directly Inherited
bet people who pray regularly have certain enlarged
portions of their brains!
is not necessarily that the traits that facilitate
homosexuality are themselves bad; perhaps many are gifts. Athleticism
is a generally good thing, and we think highly of
people who satisfy their athletic impulses as, say,
outstanding BBPs. Not so the fellow who merely becomes a thug.
Updated: 13 July 2002