They Study about Homosexuality

SIMON LEVAY-BRAIN DIFFERENCES

The first “significant” published study that indicated a possible biological role for homosexuality came from Simon LeVay, who was then at the Salk Institute for Biological Studies in San Diego, California. In 1991, Dr. LeVay reported subtle differences between the brains of homosexual and heterosexual men (1991). LeVay measured a particular region of the brain (the interstitial nuclei of the anterior hypothalamus-INAH) in postmortem tissue of three distinct groups: (1) women; (2) men who were presumed to be heterosexual; (3) and homosexual men.

LeVay’s Reported Findings

LeVay reported that clusters of these neurons (INAH) in homosexual men were the same size as clusters in women, both of which were significantly smaller than clusters in heterosexual men. LeVay reported that the nuclei in INAH 3 were “more than twice as large in the heterosexual men as in the women. It was also, however, more than twice as large in the heterosexual men as in the homosexual men” (1991, 253:1034). This difference was interpreted as strong evidence of a biological link to homosexuality. LeVay’s assumption was that homosexual urges can be biologically based-so long as cluster size is accepted as being genetically determined.

Problems with LeVay’s Study

When looking at the methodology of the LeVay study, one of the key problems is that the study has never been reproduced. As William Byne noted, LeVay’s work

has not been replicated, and human neuroanatomical studies of this kind have a very poor track record for reproducibility. Indeed, procedures similar to those LeVay used to identify nuclei have previously led researchers astray (1994, 270[5]:53, emp. added).

Additionally, of nineteen homosexual subjects used in the study, all had died of complications of acquired immunodeficiency syndrome (AIDS). AIDS has been shown to decrease testosterone levels, so it should be expected that those who suffered from that condition would have smaller INAH. Byne continued his comments on LeVay’s work.

His inclusion of a few brains from heterosexual men with AIDS did not adequately address the fact that at the time of death, virtually all men with AIDS have decreased testosterone levels as the result of the disease itself or the side effects of particular treatments. To date, LeVay has examined the brain of only one gay man who did not die of AIDS (270:53).

Furthermore, in a scientific environment where controls and standards are a necessity, LeVay did not possess a complete medical history of
the individuals included in his study. He therefore was forced to assume the sexual orientation of the non-AIDS victims as being heterosexual, when some may not have been. In addition, bear in mind that he had no evidence regarding the sexual orientation of the women whose brains he examined. LeVay has admitted:

It’s important to stress what I didn’t find. I did not prove that homosexuality is genetic, or find a genetic cause for being gay. I didn’t show that gay men are born that way, the most common mistake people make in interpreting my work. Nor did I locate a gay center in the brain (as quoted in Byrd, et al., 2001, emp. added).

Many have argued that what LeVay discovered in the brains of those he examined was only a result of prior behavior, not the cause of it. Mark Breedlove, a researcher at the University of California at Berkeley, has demonstrated that sexual behavior has an effect on the brain. In referring to his own research, Breedlove commented: “These findings give us proof for what we theoretically know to be the case-that sexual experience can alter the structure of the brain, just as genes can alter it…. [I]t is possible that

differences in sexual behavior cause (rather than are caused by) differences in the brain” (as quoted in Byrd, et al., parenthetical item in orig.). Considering this type of research, it makes sense that a homosexual lifestyle (and/or the AIDS condition) could alter the size of the nuclei LeVay was measuring.

What exactly did LeVay find? In actuality, not much. He did observe slight differences between the groups-if you accept the method he used for measuring the size of the neuron clusters (and some researchers do not). When each individual was considered by himself, there was not a significant difference; only when the individuals involved in the study were considered in groups of homosexuals vs. heterosexuals did differences result. Hubbard and Wald commented on this lack of difference:

Though, on average, the size of the hypothalamic nucleus LeVay considered significant was indeed smaller in the men he identified as homosexual, his published data show that the range of sizes of the individual samples was virtually the same as for the heterosexual men. That is, the area was larger in some of the homosexuals than in many of the heterosexual men, and smaller in some of the heterosexual men than in many of the homosexuals. This means that, though the groups showed some difference as groups, there was no way to tell anything about an individual’s sexual orientation by looking at his hypothalamus (1997, pp. 95-96, emp. added).

Being homosexual himself, it is no surprise that LeVay observed:

“…[P]eople who think that gays and lesbians are born that way are more likely to support gay rights.” 

In a Newsweek article, LeVay was quoted as saying, 

“I felt if I didn’t find any [difference in the hypothalamuses], 

I would give up a scientific career altogether” 

(as quoted in Gelman, et al., 1992, p. 49). Given how (poorly) twisted LeVay’s data are,

and his own personal bias, his abandonment of science

may have ultimately been of greater service.

Brain Plasticity-A Fact Acknowledged by All Neuroscientists

Today, scientists are keenly aware of the fact that the brain is not as “hard-wired” or permanently fixed as once thought-an important factor that LeVay failed to acknowledge. One of the properties of plastic is flexibility-many containers are made out of plastic so that they will not shatter when dropped. In a similar manner, the brain was once considered to be rigid, like Ball® jars used for canning-but we now know the brain is “plastic” and flexible, and able to reorganize itself.

Research has shown that the brain is
able to remodel its connections and grow larger, according to the specific areas that are most frequently utilized. Given that we know today that the brain exhibits plasticity, one must ask if the act of living a homosexual lifestyle itself might be responsible for the difference LeVay noted? Commenting on brain plasticity, Shepherd noted:

The inability to generate new neurons might imply that the adult nervous system is a static, “hard-wired” machine. This is far from the truth. Although new neurons cannot be generated, each neuron retains the ability to form new processes and new synaptic connections (1994).

Interestingly, since Shepherd’s textbook was published, additional research has even documented the ability of neurons to be generated within certain areas of the brain. This information must be considered when examining comparative anatomical experiments such as LeVay’s. These cortical rearrangements that occur are not as simple as unplugging a lamp and plugging it into another socket. The changes observed by researchers indicate that if the brain were represented by a home electrical system, then many of the wires within the walls would be pulled out, rewired to different connections in different rooms, new outlets would appear, and some would even carry different voltages. Due to the colossal connectivity that takes place within the brain, any “rewiring” is, by its very nature, going to have an effect on several areas-such as INAH3. Scientists understand these things, yet LeVay’s work is still mentioned as alleged support for the so-called gay gene.

BAILEY AND PILLARD-THE FAMOUS “TWINS” STUDY

One of the most frequently cited studies used in promoting the genetics of sexual orientation is a 1952 study by Kallmann. In this famous work, he reported a concordance rate (or genetic association) of 100% for sexual orientation among monozygotic (identical) twins (1952, 115:283). This result, if true, would prove nearly insurmountable for those people who doubt the biological causation of homosexuality. However, Kallmann subsequently conjectured that this perfect concordance was an artifact, possibly due to the fact that his sample was drawn largely from mentally ill and institutionalized men (see Rainer, et al., 1960, 22:259). But Kallmann’s research opened the door to twin studies in regard to sexual orientation.

Michael Bailey and Richard Pillard, researchers at Northwestern University and the Boston University School of Medicine, carried out a similar experiment, examining 56 pairs of identical twins, 54 pairs of fraternal twins, 142 non-twin brothers of twins, and 57 pairs of adoptive brothers (1991, 48:1089-1096). Bailey and Pillard were looking to see if homosexuality was passed on through familial lines, or if one could point to environmental factors as the cause. Their hypothesis: if homosexuality is an inherited trait, then more twin brothers would be expected to have the same orientation than non-twin or non-biological brothers.

Their Reported Findings

52% of identical (monozygotic) twins of homosexual men were homosexual

22% of fraternal (dizygotic) twins were likewise homosexual

11% of adoptive brothers of homosexual men were homosexual

9.2% of non-twin biological siblings reported homosexual orientations (Bailey and Pillard, 1991, “A Genetic Study of Male Sexual Orientation”)

48% of identical twins of homosexual women were likewise homosexual

16% of fraternal (dizygotic) twins were likewise homosexual

6% of adoptive sisters of homosexual women were likewise homosexual (Bailey and Benishay, 1993, “Familial Aggregation of Female Sexual Orientation”)

Problems with Bailey and Pillard’s Study

While the authors acknowledged some of the flaws with their research, they still were quoted in Science News as saying: “Our research shows that male sexual orientation is substantially genetic” (as quoted in Bower, 1992, 141:6). However, the most glaring observation is that clearly not 100% of the identical twins “inherited” homosexuality. If there was, in fact, a “gay gene,” then all of the identical twins should have reported a homosexual orientation. And yet, in nearly half of the twins studied, one brother was not homosexual. In a technical-comment letter in Science, Neil Risch and colleagues pointed out:

“The biological brothers and adoptive brothers showed approximately the same rates. This latter observation suggests that there is no genetic component, but rather an environmental component shared in families” (1993, 262:2063).

In fact, more adoptive brothers shared homosexuality than non-twin biological brothers. If there was a genetic factor, this result would be counter to the expected trend. Byne and Parsons noted:

However, the concordance rate for homosexuality in nontwin biologic brothers was only 9.2-significantly lower than that required by simple genetic hypothesis, which, on the basis of shared genetic material, would predict similar concordance rates for DZ [dizygotic] twins and nontwin biologic brothers. Furthermore, the fact that the concordance rates were similar for nontwin biologic brothers (9.2%) and genetically unrelated adoptive brothers (11.0%) is at odds with a simple genetic hypothesis, which would predict a higher concordance rate for biological siblings (1993, 50:229).

A more recently published twin study failed to find similar concordance rates.
King and McDonald studied 46 homosexual men and women who were twins.
The concordance rates that they reported were 10%, or 25% with monozygotic twins-depending on
whether or not the bisexuals were included along with the homosexuals.

The rates for dizygotic twins were 8% or 12%, again, depending on whether bisexuals were included (King and McDonald, 1992). Byne and Parsons commented: “These rates are significantly lower than those reported by Bailey and Pillard; in comparison of the MZ [monozygotic] concordance rate, including bisexuals (25%), with the comparable figure from Bailey and Pillard (52%)” (p. 230).

They went on to observe: “Furthermore, if the concordance rate is similar for MZ and DZ twins, the importance of genetic factors would be considerably less than that suggested by Bailey and Pillard” (p. 230, emp. added).

Another factor that may have had a drastic affect on the results of this study (and other similar studies) centers on methodology. Bailey and Pillard did not study a random sample of homosexuals. Instead, the subjects were recruited through advertisements placed in homosexual publications. This method can be deemed questionable because it is highly dependent on the readership of those publications and on the motives of those who respond. Thus, it may lead to skewed results-for example, inflated rates of concordance in identical twins owing to preferential participation (see Baron, 1993). Hubbard and Wald observed:

The fact that fraternal twins of gay men were roughly twice as likely to be gay as other biological brothers shows that environmental factors are involved, since fraternal twins are no more similar biologically than are other biological brothers.

If being a fraternal twin exerts an environmental influence, it does not seem surprising that this should be even truer for identical twins, who the world thinks of as “the same” and treats accordingly, and who often share those feelings of sameness (1997, p. 97).

In summarizing their findings, Byne and Parsons stated:
“Critical review shows the evidence favoring a biologic theory to be lacking” (50:228).
Commenting on Bailey and Pillard’s report, researchers Billings and Beckwith wrote:

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 (1993, p. 60).

When evaluated scientifically, twin studies fail to provide any valid support for the longed-for “gay gene.”