master’s thesis under the supervision of psychologist Lori Brotto at the University of British Columbia, found that asexual men have a higher number of older brothers than a comparison sample of heterosexual men. No one yet has conducted a study on whether the older brother effect in asexual men is restricted to biological (versus non- biological) older brothers, but the pattern of sibling effects in the Yule study is very similar to those observed in many similar studies of male homosexuality.
The discussion above places a heavy emphasis on prenatal mechanisms, such as hormones organizing brain structures during fetal development.{We can add to this evidence the research mentioned in chapter 6 showing that asexual women have atypical menarche onset (Bogaert, 2004). There is also evidence that asexual people may be somewhat shorter than sexual people (Bogaert, 2004). Atypical menarche and stature are both potential markers of altered biological development, including an altered prenatal development. Interestingly, there is evidence of atypical height patterns in gays and lesbians, although this research is not consistent and may be subject to non- biological interpretations (Bogaert & McCreary, 2011).} What about current or circulating hormones affecting asexuality? Do asexual people have low circulating hormones that reduce sex drive, and minimize their sexual attractions?
As mentioned in chapter 2, prior to the 1970s, gay men were sometimes administered high levels of testosterone. This was done because “reparative-oriented” clinicians felt that this hormone treatment could change gay men’s orientation. Yet it did not make them attracted to women; it just made them horny for more sex with men! The problem with this approach, aside from the ethics of it, was that gay men’s orientation was already determined, perhaps even before birth, and thus administering testosterone in adolescence and adulthood just “activated” or stimulated their sex drives. So the testosterone worked like fuel on the fire of whatever disposition (i.e., brain organization) was already there in the first place.
By the same token, it is unlikely that we can change many asexual people’s orientation by administering sex hormones. Thus, like gay men, asexual people’s underlying attractions (to no one, in this case) are unlikely to be changed by such interventions, although they may make the masturbating asexuals masturbate even more (see chapter 5)! Indeed, the fact that some asexual people are masturbating already (and some do so frequently) means that, at least for these asexual people, their asexuality is not a sex-drive issue, and thus their underlying sexual connection to others is unlikely to change with added hormones. Finally, as mentioned in chapter 3, there is little evidence that asexuality in animals (the so-called duds in rodents or NORs in rams) is the result of low levels of circulating or activating hormones (Adkins-Reagan, 2005; Perkins, Fitzgerald, & Price, 1992).{Does this mean that no asexual person would ever become sexual (e.g., develop sexual attractions) by taking testosterone? Not necessarily. Although the majority of asexual people likely do not have a “hormone deficiency,” there is always a possibility that some asexual people have lower-than-average testosterone or other hormones relative to sexual people. For example, low hormone levels in some asexual people may occur because of a health condition (for some evidence of this, see my original article published in 2004). Also, it is possible that some asexual people with average hormone levels who take abnormally high testosterone could raise their sex drive and, perhaps, develop some level of sexual attraction for others. There are at least two issues here, though: First, as mentioned, there is currently little evidence that asexual people, as a whole, have lower testosterone levels than average sexual people. Second, is it ethical to administer abnormally high hormones to an asexual person if asexuality, arguably, is not a disorder (see also chapters 8 and 9)?}
People often suggest to me that there
Research suggests that some atypical sexual attractions partly result from atypical rearing events, including sexual abuse (Seto, 2008). This fact raises the possibility that asexuality—as it is also an unusual form of sexual attraction—may be caused by such events. These traumatic events may be experienced very negatively and disrupt any sexual interest or attraction that normally arises in an individual. Thus, traumatic events could shut down an emerging sexuality. These events may also be coupled with (or interact with) other predisposing factors—such as prenatal influences—that could seal the deal on an individual’s asexuality.
However, there is no direct evidence that sexual abuse causes asexuality. We must also be cautious about overstating the role of sexual abuse in the etiology of atypical sexual attractions, as many people exposed to such abuse—traumatic as it may be at the time—will not develop an unusual sexuality or other long-term consequences (Rellini & Meston, 2007; Rind, Tromovitch, & Bauserman, 1998).
Recall that one of the themes of this book is that asexuality is a diverse phenomenon. The diverse patterns of asexuality are often gender related, with men likely to show one pattern, and women to show another. Masturbation experience is a good example of how the diversity in asexuality people is often gender related: Only some asexual people masturbate, and they tend to be men. Women may thus be more likely than men to be asexual, because the former are less likely to masturbate (see chapter 6). Masturbation may act as “conditioning” trials leading to the development of strong, enduring attractions to others, particularly if the masturbation is paired with images of others. Thus, another environmental influence affecting the development of asexuality may be a lack of early sexual experimentation (i.e., childhood/adolescent masturbation with fantasy). Consistent with this view, some theorists have argued that sexual attraction to others results from arousal experiences—including masturbation—directed at or with others (Storms, 1981).
Sexual attraction may also emerge from exposure to and familiarity with same-sex or opposite-sex peers (Bem, 1996). If, for example, a boy’s gender identity and role are traditional—for instance, engaging in traditional “masculine” behaviors, such as rough-and-tumble play and sports with other boys—girls may become “exotic” and hence, ultimately, sexually arousing. Thus, the boy may develop permanent attractions to the erotically charged opposite sex.
But what if this boy has little contact with and no identification with peers? Would this boy’s dis-identification with both sexes create, at least in some, an ambivalence to both and, hence, a sexual disinterest in all people later on life—that is, asexuality?
At this point, the role of the environment in asexual development, including childhood events (e.g., trauma), masturbation, and peers—remain a mystery. Research on asexual people has collected only basic information on their social environments: education, ethnicity, and social class (Bogaert, 2004; Bogaert, in press-a). Yet this information, limited as it may be, suggests that some asexual people have been exposed to an atypical environment relative to a standard, white, middle- or upper-class environment occurring in most Western societies. Asexual people are, on average, more likely to come from lower-class homes than sexual people. They are also somewhat lower in education, relative to sexual people. Finally, asexual people are, on average, more likely to have a nonwhite ethnicity than sexual people. Are these circumstances a proxy for unusual social circumstances during childhood and adolescence? Could they have an impact on sexual development through, say, increased exposure to some traumatic events that occur disproportionately in some lower-class homes, or perhaps through fewer peer interactions as a result of less school-based education? Could ethnic differences between asexual and sexual people indicate that some asexual people have been not been “acculturated” to a sexualized Western society (Brotto, Chik, Ryder, Gorzalka, & Seal, 2005)? These questions are intriguing but remain unanswered and await further research.
Summary
One of the themes of this book is that the study of asexuality informs our understanding of sexuality. This is also true in the case of etiology. Prenatal mechanisms (e.g., genes, hormones, maternal immune response) potentially underlying asexuality may be the same ones that underlie traditional sexual orientations (gay, straight, and bisexual), and sexual variability generally. Thus, to have some understanding of one is to have some understanding of the other. This also holds true for nonbiological influences on sexuality. For example, peers and masturbation (and the role of conditioning) may play some role in sexualizing or de-sexualizing a person, depending on how these influences play themselves out in the individual.
You could say that I am an expert on sexual orientation development, as my research work in this area is
