June 27, 2006

Could having older brothers make you gay?

Posted in Politics, Relationships at 11:35 pm by Calico Jack

According to a new study funded by the Social Sciences and Humanities Research Council of Canada, men who have several older brothers are more likely to be gay. Of course, the media is going to treat this claim with due consideration and careful scrutiny, right? Let’s take a look at the AP article to see how this information is presented to the public:

“It’s likely to be a prenatal effect,” said Anthony F. Bogaert of Brock University in St. Catharines, Canada, “This and other studies suggest that there is probably a biological basis for” homosexuality.

Okay, the conclusion is that a person’s sexual orientation could be biological, likely being formed while still in the womb. Therefore, the data must support that claim for it to be a valid conclusion. So far, so good.

S. Marc Breedlove of Michigan State University said the finding “absolutely” confirms a physical basis.

“Anybody’s first guess would have been that the older brothers were having an effect socially, but this data doesn’t support that,” Breedlove said in a telephone interview.

The only link between the brothers is the mother and so the effect has to be through the mother, especially since stepbrothers didn’t have the effect, said Breedlove, who was not part of the research.

First of all, why did the AP interview a professor who had absolutely nothing to do with the study in the first place? His credentials are never listed in this article; how are we supposed to know whether or not he is qualified to actually comment on this study?

I did some research, and here’s what I came up with: S. Marc Breedlove earned a Ph.D in psychology from UCLA in 1982, after which he became a professor of psychology at UC Berkeley. He transferred to Michigan State University in 2001, receiving the Barnett Rosenberg Chair in Neuroscience and a tenured professorship in the departments of psychology and zoology. His areas of research include “sexual differentiation of the brain and spinal cord, morphological sex differences in the nervous system, and permanent and transient effects of hormones on neurons.” So what exactly does that mean? Well, he’s published papers on various subjects such as “Finger-length ratios and sexual orientation,” “Differences in finger length ratios between self-identified butch and femme lesbians,” and “Sexual dimorphism in digit-length ratios of laboratory mice.”

I’m speechless. Back to the study.

Bogaert studied four groups of Canadian men, a total of 944 people, analyzing the number of brothers and sisters each had, whether or not they lived with those siblings and whether the siblings were related by blood or adopted.

He reports in a paper appearing in Tuesday’s issue of Proceedings of the National Academy of Sciences that having several biological older brothers increased the chance of a man being gay.

It’s an effect that can be detected with one older brother and becomes stronger with three or four or more, Bogaert said in a telephone interview.

But, he added, this needs to be looked at in context of the overall rate of homosexuality in men, which he suggested is about 3 percent. With several older brothers the rate may increase from 3 percent to 5 percent, he said, but that still means 95 percent of men with several older brothers are heterosexual.

Okay, let’s see…944 people divided into four groups means that there are 236 people per group. An increase in the overall rate of homosexuality among men from 3 to 5 percent means that the number of gay people in each group ranged anywhere from 7 to 11…hardly a noteworthy statistic. Keep in mind that this rate is an assumption by the researchers; without hard data it is hard to provide an accurate picture. The sample size may be large enough, but a variation of two percent is so small as to be almost meaningless. Also, notice the complete absence of a margin of error or confidence interval; this could easily eliminate any differences in the study.

Ignoring the shaky statistics, however, my one question is this: what kind of biological effect on homosexual inclination could possibly be caused by having older brothers? And why would this effect increase along with the number of older brothers that someone has?

Bogaert said he concluded the effect was biological by comparing men with biological brothers to those with brothers to whom they were not biologically related.

The increase in the likelihood of being gay was seen only in those whose brothers had the same mothers, whether they were raised together or not, he said.

Men raised with several older step- or adopted brothers do not have an increased chance of being gay.

“So what that means is that the environment a person is raised in really makes not much difference,” he said.

Just out of curiosity, where are the fathers in this research? I understand the need to study mothers, since that is the only way to support their biological claim. But solely looking at brothers and not fathers means that the researchers cannot claim with absolute certainty that environment does not matter. Have they eliminated all environmental factors in their research, allowing them to have a solid control? Or have they merely seen a correlation between two pieces of information, and made that their theory without adequate study?

What makes a difference, he said, is having older brothers who shared the same womb and gestational experience, suggesting the difference is because of “some sort of prenatal factor.”

One possibility, he suggests, is a maternal immune response to succeeding male fetuses. The mother may react to a male fetus as foreign but not to a female fetus because the mother is also female.

It might be like the maternal immune response that can occur when a mother has Rh-negative blood but her fetus has Rh-positive blood. Without treatment, the mother can develop antibodies that may attack the fetus during future pregnancies.

Whether that’s what is happening remains to be seen, but it is a provocative hypothesis, said a commentary by Breedlove, David A. Puts and Cynthia L. Jordan, all of Michigan State.

Okay, let’s review for those of you who may be lost by this incoherent mess. Based on a single small study with faulty testing and inadequate research, these “scientists” are suggesting the following:

  • There is a corellation between having older brothers and an increase in the likelihood of being gay…up to a two percent difference.
  • This effect does not matter whether or not the brothers were raised together, only that they shared the same blood, meaning that there must be a biological, not environmental, basis for this effect.
  • Since some of the brothers were not raised together, this biological effect must take place in the womb before birth, because the womb is the only invariable factor where this effect could occur.
  • To explain this pre-natal effect, these researchers raise the possibility that the maternal immune system could assault successive male fetuses, since the mother may recognize the male fetus as a foreign object and attack it.
  • Over time, as more male fetuses gestate, the mother’s immune defenses could become stronger, until eventually…what?

See, that last point is the hardest question to answer. If a predisposition towards homosexuality is caused by a reaction of the mother’s immune system, could that mean that such tendencies are an aberration? That raises a whole slew of interesting questions. However, the point is moot, since this study is inherently flawed. These researchers made a mistake that is inexcusable for a high school student, let alone professional scientists. They assumed that because there was a correlation between two things, a causation must follow.

I won’t rule out that there could be a biological predisposition towards homosexuality, but this study does nothing to advance that claim. The media are making a much bigger deal out of this than they should be doing. To spread this story–sans critique–all over television and the internet is irresponsible. I suggest that the next time a story such as this is released, reporters and scientists take a hard look at the data presented. Doing so will serve the public much better than blindly accepting a faulty study.

1 Comment »

  1. Peter said,

    Very interesting, On the ball hoho. Happy New year, take Care.

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