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You can tell a lot about a person just by looking at their face— their age, their gender, and even their emotional state. Now, researchers at Nipissing University in Canada, say facial features can also reveal a person's sex drive and how likely they are to cheat in relationships.

The study, published in Archives of Sexual Behavior, found that both men and women with shorter, wider faces were more sexually motivated, meaning they have higher libidos. Men with very wide faces (calculated as facial width-to-height ratio, or FWHR) had a higher sex drive than others and were more open to casual sex that does not involve love or commitment. They also considered being unfaithful to their significant others.

"Together, these findings suggest that facial characteristics might convey important information about human sexual motivations," Steven Arnocky, lead author of the study, said in a statement.

Arnocky and his colleagues already knew that the dimensions of a person's face are linked to certain psychological and behavioral traits. For example, a 2014 study published in Psychological Science found that women perceived men with wider faces as more dominant and more attractive within three minutes of face-to-face speed dating. The women saw a high FWHR as more dominant and having more romantic potential, but only for short-term relationships.

That finding prompted the researchers to investigate whether FWHR could predict sex drive among both men and women. In two separate studies, Arnocky, a psychologist focused on sex and human behavior, examined correlations between sexuality and facial features. In the first study, 145 male and female undergraduate students in romantic relationships were asked questions about their interpersonal behavior and sex drive, and their FWHR was measured using photographs. In the second study, an extended version of the first, 314 students answered additional questions about sociosexual orientation (attitudes toward casual sex, for example) and intended infidelity.

According to their report, FWHR was significantly correlated with sex drive. Just by knowing an individual's FWHR, the researchers could predict what that person reported about their sex drive. The link held true for both genders.

Researchers believe these FWHR-associated behaviors can be explained by sex hormones, specifically testosterone. Men and women's sexual motives and behavior are partially modulated by testosterone. During puberty, testosterone is linked to later sexual motives and behavior in men and women. For example, a 2011 study published in Hormones and Behavior found both partnered men and women who reported either a greater desire for casual sex or sexual behavior had testosterone levels that were comparable to their single counterparts. Single men and women are known to have higher testosterone compared to those who are partnered up.

Arnocky's study could spur further research on whether the effects of FWHR can be detected in adolescence and whether they remain throughout adulthood. If this correlation holds through later adulthood, the link could provide insights on long-term relationships among older adults.

Long story short? A person’s sexual preferences could actually be written all over their face.