New research further suggests biological link to sexual orientation
A new study published with substantial involvement from Brock University scholars argues that male sexual orientation is likely determined in utero. Brock Psychology Professor Tony Bogaert, the work’s primary author, called the result a culmination of 20 years of work on the “older brother effect.”
This effect, which Bogaert first identified in the 1996, suggests that men with older brothers are more likely to identify as homosexual. The existence of the older brother effect was supported by independent studies across cultures, leading Bogaert to believe that biological causes were at play. Having found this line of research, he and a rotating team pursued it for many years.
“We first found this link a long time ago, but this most recent study dug more into why exactly this link exists,” said Bogaert. Essentially, the team’s analysis of the mothers of gay sons showed that those with male children born before the homosexual son had higher levels of particular antibodies.
The team tested 16 women with no sons, 72 mothers with heterosexual sons, 31 mothers of gay sons with no older brothers, 23 mothers of gay sons with older brothers, and a control group of 12 men.
The women’s antibody reactivity was measured to two proteins found only in males, both of which are expressed in the male fetal brain.
The team found that mothers of gay sons, especially those with older brothers, had significantly higher antibody levels to one protein than did the control samples of women, including mothers of heterosexual sons.
“It seems that some women during their first male pregnancy, or just after their first male birth, begin to detect this foreign substance and start to develop an immune response,” said Bogaert.
The results of the study suggest that this immune response changes the brain development in later born males, since these particular antibodies are found only in men.
“Presumably, this alters the way male nerve cells communicate with each other,” said Bogaert.
“This is why the results are so interesting, because they get right at the question of how and why sexual attraction occurs in all people.”
However, the Bogaert cautions that the effects are modest and the likelihood of a male child being born gay is still small — even if they have multiple male siblings.
“The vast majority of men with older brothers are still heterosexual, but it says something very broad about sex and gender development.”
Bogaert acknowledged that discussion of homosexuality is fraught with political and philosophic questions, but emphasized that an alteration does not mean unnatural.
“Logically speaking, there are all sort of ways in which biological processes lead to atypical results, but this does not mean that it is a disorder.”
According to Bogaert, much of the early research into homosexuality in the 1950s, ‘60s, and the early ‘70s was related to trying to find a “cure.” More recent work, on the other hand, seeks instead to understand the causes of homosexuality without any interest in therapy or alteration.
Bogaert, who is 54, has also spent part of his career studying asexual individuals—those who profess to be sexually attracted to no one at all.
“A lot of my work is lab-based, but with the study of asexuality I’ve done work trying to understand it through lived experience,” explained Bogaert. “Trying to identify what is and what isn’t a disorder, and I have a pretty high bar for what constitutes a disorder.”
In Bogaert’s eyes, to be considered a disorder a condition must be causing stress upon an individual—and a particular kind of stress, at that.
“Once you deconstruct a lot of the stress, you see that it’s not the individual that has a disorder, it’s the general society that has the problem.”
Bogaert acknowledged that there are “diverse reactions” to the kind of work that his team does, but said that he believed that on average proponents of the gay rights movement are “positive to neutral” on the work that argues that sexual orientation is not a conscious choice.
Cynthia Nixon, an actor who appeared in Sex and the City, made headlines in 2012 when she said that being homosexual was a choice for her.
“I understand that for many people it’s not, but for me it’s a choice, and you don’t get to define my gayness for me,” she told the New York Times.
“Defining gayness” is another tricky problem, the difficulty of which Bogaert fully realizes.
“In our study, the homosexual men were all identified by the mothers that were part of the group,” he said. “We did this partly because it was convenient, but also because these mothers probably have good reason for saying that their sons are gay.”
Some gender scholars, including Jane Ward of the University of California, Riverside, argue that “desires are oriented and re-oriented based on our experiences throughout our lives.” According to Ward, gay activists initially treated sexuality more like a religion, the perspective that she is more in agreement with.
“People aren’t born with their religions,” she writes. “They’re born into religious cultures, and they can convert if they’d like.” But Ward says that activists came to believe that this approach wasn’t the most politically effective, and changed the gay rights movement’s tack.
“There was a shift, and the leaders of the movement chose to jump on board with a less nuanced argument that people already understood: just like race, people are born with their homosexuality,” she argues.
Bogaert’s research certainly puts him in opposition to Ward and others like her, at least to some degree, though he is quick to mention that human sexuality is complicated. In his undergraduate lecture courses, he devotes part of the semester to discussing sexuality, and said that students generally find the topic engaging.
“Most people understand that there’s a basic biology, and that we have basic motivations,” said Bogaert, adding that students are generally open to discussion and not “put off by the science-y perspective.”
After these basic motivations are examined, Bogaert talks to his classes about the broader social implications of sexuality.
“We discuss the social influences on sexual behaviours,” he said. “Not only are there different expressions in different cultures, there are different expressions from one house to the next.”
The broader question, according to Bogaert, and the one which he poses to his classes, is: why are we attracted to people in the first place?
The point of the work is trying to find out “who we are and why we develop,” said Bogaert.
“It’s an effort to try and understand. And understanding is better than not understanding.”
