There has long been skepticism among both scientists and laypersons that male bisexual orientation exists; paper finds robust evidence that male sexual orientation is expressed on a continuum

Robust evidence for bisexual orientation among men. Jeremy Jabboura et al. Proceedings of the National Academy of Sciences, Jun 2020. https://www.pnas.org/content/pnas/early/2020/07/14/2003631117.full.pdf

Significance: There has long been skepticism among both scientists and laypersons that male bisexual orientation exists. Skeptics have claimed that men who self-identify as bisexual are actually homosexual or heterosexual. (The existence of female bisexuality has been less controversial.) This controversy can be resolved using objective, genital responses of men to male and female erotic stimuli. We combined nearly all available data (from eight previous American, British, and Canadian studies) to form a dataset of more than 500 men, much larger than any previous individual study, and conducted rigorous statistical tests. Results provided compelling evidence that bisexualidentified men tend to show bisexual genital and subjective arousal patterns. Male sexual orientation is expressed on a continuum rather than dichotomously.

Abstract: The question whether some men have a bisexual orientation—that is, whether they are substantially sexually aroused and attracted to both sexes—has remained controversial among both scientists and laypersons. Skeptics believe that male sexual orientation can only be homosexual or heterosexual, and that bisexual identification reflects nonsexual concerns, such as a desire to deemphasize homosexuality. Although most bisexual-identified men report that they are attracted to both men and women, self-report data cannot refute these claims. Patterns of physiological (genital) arousal to male and female erotic stimuli can provide compelling evidence for male sexual orientation. (In contrast, most women provide similar physiological responses to male and female stimuli.) We investigated whether men who self-report bisexual feelings tend to produce bisexual arousal patterns. Prior studies of this issue have been small, used potentially invalid statistical tests, and produced inconsistent findings. We combined nearly all previously published data (from eight previous studies in the United States, United Kingdom, and Canada), yielding a sample of 474 to 588 men (depending on analysis). All participants were cisgender males. Highly robust results showed that bisexual-identified men’s genital and subjective arousal patterns were more bisexual than were those who identified as exclusively heterosexual or homosexual. These findings support the view that male sexual orientation contains a range, from heterosexuality, to bisexuality, to homosexuality.

Keywords: sexual orientation | bisexuality | sexual arousal | Kinsey scale | sexuality