Women who are not entirely straight or gay tend to have slightly higher levels of psychopathic traits and a more casual attitude towards sex, according to new research published in the journal Evolutionary Psychological Science. The study also provides more evidence that bisexuality is a distinct sexual orientation in women.

“I was mainly interested in this topic because certain patterns seemed to be accruing in the academic literature regarding bisexual individuals, and bisexual women in particular. Bisexual women differ in some important ways––such as personality, sex drive, and relative openness to casual sex––from both their heterosexual and their lesbian counterparts,” said Scott W. Semenyna of University of Lethbridge, the corresponding author of the study.

“My specific interest in the overlap between sexual orientation, Dark Triad traits (psychopathy, narcissism, and Machiavellianism), and sociosexuality sprang from two key findings. First, bisexual women report elevated sociosexuality (i.e., greater comfort with, desire for, and engagement in uncommitted sexual activity) compared to both heterosexual or lesbian women. Second, bisexual women report slightly lower levels of two personality traits––honesty/humility, and conscientiousness––than other sexual orientation groups.”

“These personality traits have both been related to higher levels of Dark Triad traits, and also greater sociosexuality,” Semenyna told PsyPost. “These past findings suggest that female sexual orientation may share some unique relationships with both personality, and sexuality related variables, and I wanted to dig deeper into those potential connections.”

The researchers found that bisexual women tended to score higher on measures of sociosexuality and psychopathy than strictly heterosexual and lesbian women.

The findings were based on two surveys of a total of 1,093 female students at a Midwestern Canadian University. The study utilized the Kinsey scale of sexual attraction, which ranges from exclusively heterosexual to exclusively homosexual. In the very middle of the scale are individuals who are mostly heterosexual, equally heterosexual and homosexual, and mostly homosexual.

“The big-picture take away from this study is that sociosexuality shares a curvilinear (inverted-U) relationship with female sexual orientation,” Semenyna explained. “Heterosexual and lesbian women don’t tend to differ from one another in their relative caution towards uncommitted sexual activity. Women towards the middle of the sexual orientation spectrum, especially those who are ‘moderately bisexual,’ are somewhat less cautious about uncommitted sexual activity.”

“Alongside these shifts in sociosexuality are shifts in some Dark Triad personality traits, particularly psychopathy,” Semenyna told PsyPost. “These shifts are subtle, only about as large as typical sex differences in the traits, but they’re interesting. (Men typically score higher in all Dark Triad traits, as well as interest in casual sex, than do women.)”

“Primarily such evidence is consistent with the hypothesis that female bisexuality and female homosexuality are the result of different developmental processes. If female bisexuality and homosexuality were simply the result of the same underlying developmental processes, one would expect that any differences between heterosexual and bisexual women in personality or interest in casual sex would be even larger when comparing heterosexual and lesbian women.”

“Instead, what we observe is that lesbian and heterosexual women don’t differ in these variables, despite drastic difference in who they are sexually attracted to,” Semenyna said. “On the other hand, bisexual women are higher in these traits than heterosexual or lesbian women, while being attracted to some degree to both males and females.”

The study does have some limitations.

“While research into female sexuality and women’s sexual orientation has grown in the last few decades, we are in desperate need of more data to bridge the substantial gaps in our understanding,” Semenyna remarked.

“The biggest caveat in the present study is that the sexual orientation differences in psychopathy have not yet been replicated. The study adds support to other findings that bisexual women are more interested in casual sex, and engage in it more often (often with men). Other aspects of the study require replication, ideally by independent researchers.”

“The other caveat is that this study was conducted on an extremely WEIRD sample (i.e., Western, Educated, Industrialized, Rich, and Democratic). It’s unclear whether these differences apply only to university students, if similar differences may exist in the general population, or what possible cross-cultural variation exists in these patterns,” Semenyna said.

“The cross-sectional nature of the study also prevents any causal connections from being drawn. First we have to establish these potential differences as reliable, then we have to interpret why these difference may exist and what they mean. In short, this study is an extremely small thread in a large tapestry that is slowly being woven, but is far from complete.”

Semenyna also emphasized that the study should not be misinterpreted as an attack on bisexuality or bisexual women.

“I’ve seen certain criticisms online of the study that it suggests that bisexual women are ‘slutty,’ or that we are trying to paint bisexual women in a negative light. Essentially the research is being accused of being ‘biphobic,'” he explained.

“I think this is unfortunate for several reasons. The first of which is that the purpose of science is to investigate and understand, and report results regardless of how well they fit our preconceptions and preferences. Scientific investigation of sexual minorities is an important step towards greater understanding, and ultimately greater acceptance.”

“The second reason is that I don’t see anything inherently wrong with people being comfortable with and pursuing casual sexual behavior, and having the freedom to do so. The sexual orientation differences in sociosexuality, as well as psychopathy, are only about as large as the typical sex differences found in these traits, with men on average scoring slightly higher than women on average,” Semenyna said.

“To suggest that these differences in sociosexuality or psychopathy paint bisexual women in a negative light is to simultaneously smear men, who similarly score higher than heterosexual women on these traits. To view normal variation (i.e., diversity) in human personality and sexual behavior as somehow problematic is ultimately counterproductive to both scientific progress on these topics, and social acceptance.”

The study, “Not Straight and Not Straightforward: the Relationships Between Sexual Orientation, Sociosexuality, and Dark Triad Traits in Women“, Charlene F. Belu, Paul L. Vasey, and P. Lynne Honey.

