ome people say we should settle gay rights disputes on
the basis of the Old Testament. I say we should rely on blinking
patterns.
In case you've misplaced your latest copy of
Behavioral Neuroscience, there's a fascinating article about how people
blink. It turns out that when males and females are exposed to a loud
noise, they blink in somewhat different ways — except that lesbians appear
to blink like men, not like women.
The study (peer-reviewed but based on a small
sample) is the latest in a growing scientific literature suggesting that
sexual preferences may be not simply a matter of personal preference but
part of our ingrained biology. Indeed, some geneticists believe that
sexual orientation in men (though not women) may be determined in part by
markers in the Xq28 chromosomal region.
One needs to be wary of these kinds of studies,
partly because researchers drawn toward this field may have subconscious
biases of their own. Moreover, many of the studies on the biological basis
of homosexuality are flawed by small numbers or by the difficulty of
finding valid random samples of gays and heterosexuals.
Still, while the data has problems, it is piling up
— there are at least seven studies on twins. If there is a genetic
component to homosexuality, one would expect identical twins to share
sexual orientation more than fraternal twins, and that is indeed the case.
An identical twin of a gay person is about twice as likely to be gay as a
fraternal twin would be.
Earlier this year, the journal Personality and
Individual Differences published an exhaustive review of the literature
entitled "Born Gay?" After reviewing the twin studies, it concluded that
50 to 60 percent of sexual orientation might be genetic.
Many studies also suggest that sexual orientation
may be linked to differences in brain anatomy. Compared with straight men,
gay men appear to have a larger suprachiasmatic nucleus, a part of the
brain that affects behavior, and some studies show most gay men have a
larger isthmus of the corpus callosum — which may also be true of
left-handed people. And that's intriguing because gays are 39 percent more
likely to be left-handed than straight people.
Now look at your fingers. Men typically have a ring
finger that is longer than the index finger, while in women the two are
about the same length. However, two studies have suggested that lesbians
have finger-length ratios that are more like those of men than of
women.
Studies suggest that ring-finger length has to do
with the level of androgens in the womb, and that may help explain another
puzzle of homosexuality: a male is more likely to be gay if he has older
brothers. It doesn't matter if he has older sisters, but for each older
brother he is about 33 percent more likely to be gay. Some scientists
speculate that a woman's body adjusts the androgen level in her womb as
she has more sons, and that the androgens interact with genes to produce
homosexuality.
O.K., these theories are potentially junk science
until the studies are replicated with much larger numbers. But we also
shouldn't ignore the accumulating evidence.
"There is now very strong evidence from almost two
decades of `biobehavioral' research that human sexual orientation is
predominantly biologically determined," said Qazi Rahman, the University
of London researcher who led the blinking study. Many others don't go that
far, but accept that there is probably some biological
component.
Gays themselves are divided. Some welcome these
studies because they confirm their own feeling that sexual orientation is
more than a whim. Others fret that the implication is that homosexuals are
abnormal or defective — and that future genetic screening will eliminate
people like them.
For me the implication, if these studies are to
believed, is different: It is that something is defective not in gays, but
in discrimination against them.
A basic principle of our social covenant is that we
do not discriminate against people on the basis of circumstances that they
cannot choose, like race, sex and disability. If sexual orientation
belongs on that list (with the caveat that the evidence is still murky),
then should we still prohibit gay marriage and bar gays from serving
openly in the armed forces?
Can we countenance discrimination against people for
something so basic as how they blink — or whom they
love?
