Anthony F. Bogaert

Adult attachment and sexual behavior

The relations between adult attachment processes and sexuality were examined in a community sample of 792 young adults (327 men and 465 women) from the Niagara region of Canada. Participants completed questionnaires that included Simpson’s (1990) measure of adult attachment, self-reported physical attractiveness, erotophilia, and a variety of sexual behavior measures (e.g., number of sexual partners, age of first sexual experience, frequency of sexual behaviors in the past year, whether an affair had occurred in the past year, and consistent condom usage). The sexuality measures were factor analyzed to extract common factors. The results were modest, but a number of significant relationships between sexuality and attachment were observed. For example, people scoring higher on a secure attachment index perceived themselves as more physically attractive, whereas people scoring higher on an anxious attachment index perceived themselves as less physically attractive, had an early first intercourse (and more lifetime partners), more infidelity, and took more sexual precautions (e.g., condom usage). The results were generally stronger in women, with most of the attachment/sexuality associations in the full sample being driven by the results in women. Implications for understanding sexual variability, including high-risk sexual behavior, are discussed.

Asexuality: Prevalence and associated factors in a national probability sample

I used data from a national probability sample (N > 18,000) of British residents to investigate asexuality, defined as having no sexual attraction to a partner of either sex. Approximately 1%(n = 195) of the sample indicated they were asexual. A number of factors were related to asexuality, including gender (i.e., more women than men), religiosity, short stature, low education, low socioeconomic status, and poor health. Asexual women also had a later onset of menarche relative to sexual women. The results suggest that a number of pathways, both biological and psychosocial, contribute to the development of asexuality.

Toward a Conceptual Understanding of Asexuality

Asexuality has been the subject of recent academic (A. F. Bogaert, 2004) and public (e.g., New Scientist; CNN) discourse. This has raised questions about the conceptualization and definition of asexuality. Here the author reviews some of these issues, discusses asexuality from a sexual orientation point of view (i.e., as a lack of sexual attraction), and reviews the similarities and differences between this definition and related phenomena (e.g., hypoactive sexual desire disorder). Finally, the author concludes that the term asexuality should not necessarily be used to describe a pathological or health-compromised state.

Biodemographic comparisons of homosexual and heterosexual men in the kinsey interview data

Relations between sexual orientation and several biodemographic variables previously reported to differentiate between homosexual and heterosexual men were examined. Subjects were 4948 white, postpubertal males, who were never reared in foster homes, orphanages, or other institutions, and were never arrested or convicted on criminal charges. These were dichotomously classified as homosexual (n=844) or heterosexual (n=4104). Data came from survey interviews conducted by staff members of The Kinsey Institute for Research in Sex, Gender, and Reproduction from 1938 to 1963. Results extended previous findings that, compared with heterosexual controls, homosexual men have a later birth order, an earlier onset of puberty, and a lower body weight. Sexual orientation was weakly related or unrelated to height, paternal age, and sibling sex ratio. A more detailed analysis of the late birth order of the homosexual group showed that homosexual men have a greater number of older brothers than do heterosexual men, but they do not have a greater number of older sisters, once their number of older brothers has been taken into account.

Volunteer bias in human sexuality research: Evidence for both sexuality and personality differences in males

The extent to which personality, social behavior, and sexuality differed in undergraduate males under two different types of recruitment, volunteer and nonvolunteer, was investigated. Nonvolunteers (N=160) were ostensibly recruited for a study on personality, and volunteers (N=204) were overtly recruited for a study on human sexuality. Both samples completed the same personality, social behavior, and sexuality questionnaires. Volunteers were found to be more sexually experienced, more interested in sexual variety, and more erotophilic than the nonvolunteers. In addition and contrary to most prior research, the volunteer and nonvolunteer samples also differed in personality and social behavior, with the volunteers being higher in sensation seeking and lower on measures of social conformity and rule-following behavior than the nonvolunteers. Results extend prior research suggesting limits to the generalizability of some human sexuality research.

How Many Gay Men Owe Their Sexual Orientation to Fraternal Birth Order

In men, sexual orientation correlates with the number of older brothers, each additional older brother increasing the odds of homosexuality by approximately 33%. However, this phenomenon, the fraternal birth order effect, accounts for the sexual orientation of only a proportion of gay men. To estimate the size of this proportion, we derived generalized forms of two epidemiological statistics, the attributable fraction and the population attributable fraction, which quantify the relationship between a condition and prior exposure to an agent that can cause it. In their common forms, these statistics are calculable only for 2 levels of exposure: exposed versus not-exposed. We developed a method applicable to agents with multiple levels of exposure—in this case, number of older brothers. This noniterative method, which requires the odds ratio from a prior logistic regression analysis, was then applied to a large contemporary sample of gay men. The results showed that roughly 1 gay man in 7 owes his sexual orientation to the fraternal birth order effect. They also showed that the effect of fraternal birth order would exceed all other causes of homosexuality in groups of gay men with 3 or more older brothers and would precisely equal all other causes in a theoretical group with 2.5 older brothers. Implications are suggested for the gay sib-pair linkage method of identifying genetic loci for homosexuality.

The Relation Between Sexual Orientation and Penile Size

The relation between sexual orientation andpenile dimensions in a large sample of men was studied.Subjects were 5122 men interviewed by the KinseyInstitute for Research in Sex, Gender, and Reproduction from 1938 to 1963. They were dichotomouslyclassified as either homosexual (n = 935) orheterosexual (n = 4187). Penile dimensions were assessedusing five measures of penile length and circumferencefrom Kinseys original protocol. On all fivemeasures, homosexual men reported larger penises thandid heterosexual men. Explanations for these differencesare discussed, including the possibility that these findings provide additional evidence thatvariations in prenatal hormonal levels (or otherbiological mechanisms affecting reproductive structures)affect sexual orientation development.

Interaction of fraternal birth order and handedness in the development of male homosexuality

The present study investigated evidence for an interaction between two of the best established etiologic factors, or markers of etiologic factors, in the literature on male homosexuality: fraternal birth order and hand preference. By combining five samples, the authors produced study groups of 1774 right-handed heterosexuals, 287 non-right-handed heterosexuals, 928 right-handed homosexuals, and 157 non-right-handed homosexuals. The results showed a significant (P = 0.004) handedness by older brothers interaction, such that (a) the typical positive correlation between homosexuality and greater numbers of older brothers holds only for right-handed males, (b) among men with no older brothers, homosexuals are more likely to be non-right-handed than heterosexuals; among men with one or more older brothers, homosexuals are less likely to be non-right-handed than heterosexuals, and (c) the odds of homosexuality are higher for men who have a non-right hand preference or who have older brothers, relative to men with neither of these features, but the odds for men with both features are similar to the odds for men with neither. These findings have at least two possible explanations: (a) the etiologic factors associated with non-right-handedness and older brothers-hypothesized to be hyperandrogenization and anti-male antibodies, respectively-counteract each other, yielding the functional equivalent of typical masculinization, and (b) the number of non-right-handed homosexuals with older brothers is smaller than expected because the combination of the older brothers factor with the non-right-handedness factor is toxic enough to lower the probability that the affected fetus will survive.

Fraternal Birth Order and Sexual Orientation in Pedophiles

Whether homosexual pedophiles have more older brothers (a higher fraternal birth order) than do heterosexual pedophiles was investigated. Subjects were 260 sex offenders (against children age 14 or younger) and 260 matched volunteer controls. The subjects relative attraction to male and female children was assessed by phallometric testing in one analysis, and by his offense history in another. Both methods showed that fraternal birth order correlates with homosexuality in pedophiles, just as it does in men attracted to physically mature partners. Results suggest that fraternal birth order (or the underlying variable it represents) may prove the first identified universal factor in homosexual development. Results also argue against a previous explanation of the high prevalence of homosexuality in pedophiles (25% in this study), namely, that the factors that determine sexual preference in pedophiles are different from those that determine sexual preference in men attracted to adults. An alternative explanation in terms of canalization of development is suggested.

Handedness, criminality, and sexual offending

A very large database was used to investigate whether men with a history of criminality and/or sexual offending have a higher incidence of nonright-handedness (NRH) relative to a control sample of nonoffender men. The sample (N>8000) comprised interviews by investigators at the Kinsey Institute for Sex and Reproduction in Indiana. The general offender group and a subsample of sex offenders (e.g. pedophiles) had a significantly higher rate of NRH relative to the control (nonoffender) men. In addition, evidence was found that the general criminality/NRH relationship might result from increased educational difficulties that some nonright-handers experience. In contrast, education was unrelated to the handedness/pedophilia relationship, suggesting that there may be a different mechanism underlying the handedness/pedophile relationship than the handedness/(general) criminality relationship. Finally, as a cautionary note, it is stressed that the effects are small and that NRH should not be used as a marker of criminality.