9. Testosterone and the Opposite Sex. The way men interact with others can be affected by their testosterone levels and also by the mere presence of the opposite sex. In 2011, researchers found the more elevated a man's testosterone after engaging in a competition, the more he flirts with strange women (van der Meij et al., 2011); among men who think they are socially dominant, those with high testosterone tend to be more dominant in competition with other men (and women in the study tend to think they "clicked" more with these higher testosterone men; Slatcher et al., 2011); and men's (but not women's) ability to think clearly is impaired when they're about to interact with the opposite sex (Nauts et al., 2011). The relationship between testosterone and sexual personality is almost never as simple as more testosterone means more intense sexual desire and behavior, but new studies continue to paint an ever more realistic picture of how our sex hormones can directly affect our sexual personality.

8. Sex Differences in Emotion. On average, women and men experience some emotions a little differently, such as the trend for women to experience a bit more anxiety and worry than men do. In 2011, studies found women tend to remember more negative words from a word list (even when the negative words are not actually there) than men do (Dewhurst et al., 2011); happy women (but not men) and prideful men (but not women) are seen as most sexually attractive (Tracy & Beall, 2011); and sex differences in the emotion of jealousy seemed to transcend several other features of our sexual personalities (Confer et al., 2011; Kuhle, 2011; Tagler et al., 2011). Many of our basic emotional systems are hardwired into our Homo sapiens sapiens brain, but the way these emotions are experienced and how these emotions function in our sexual lives may depend, in part, on our biological sex.

7. Sexual Personalities in Couples. Very few studies have been conducted on cultural differences in the sexual personality of couples. In 2011, a study of married couples across six cultures found some sex differences are universal (on average, husbands want more sex from their wives), but others are not (husbands are not always more possessive); a study of older couples across five cultures found women (but not men) tend to become more sexually satisfied as they age (Heiman et al., 2011); and a study of newlyweds-while not cross-cultural-interestingly found that having too forgiving a sexual personality can lead your partner to persist in their aggressive ways (McNulty, 2011). Much of our sexual personality takes place in interaction with others, and it appears that no matter the culture we are from there is no more important other than our primary long-term partner.

6. Environmental Factors Influence Sexual Personalities. There is an emerging trend that local environments and social situations can affect our sexual personalities. In 2011, an experimental study found bad smells in the immediate environment leads people to intend to use condoms (Tybur et al., 2011); a study found some cultural differences in sexuality result from people learning mate preferences by copying the preferences of high status and attractive others in their local social situations (Little et al., 2011); and a study found that extra-marital sex tends to be quite high in foraging cultures, especially among women (Scelza, 2011). It seems much of our sexual personality depends on our environments, more so than most people realize.

5. Ovulatory Status and Oral Contraception Affect Sexual Personalities. One of the most striking findings in sexual personality research is that women's desires and behaviors seem to shift across their ovulatory cycle. In 2011, a study found women who take the pill tend to choose "good guys" as mates, but end up sexually unsatisfied (Roberts et al., 2011); a study found women's personalities become warmer during their most fertile ovulatory phase (Markey et al., 2011); and another study found that when women are at their most fertile, the men around them make riskier decisions (Miller et al., 2011). These results may seem strange and many of the effects are subtle, but more and more research from labs around the world is suggesting that women's ovulation plays a key role in our sexual personalities.

4. Mate Value and Sexual Personalities. How we are viewed by others—whether we are high status, physically attractive, and so forth—can have a strong impact on the sexual experiences of ourselves and our partners. In 2011, a study found that women tend to orgasm more often when having sex with attractive partners (but not when self-pleasuring themselves, so the effect seems to come from the male partner's mate value; Puts et al., 2011); a study of foraging peoples found men who possess higher status and prestige tend to have more sexual partners (including extra-marital affairs; von Rueden et al., 2011); and a study found that women tend to shy away from attractive mates as husbands because they fear these men will be unfaithful, but this fear wasn't evident among women who are themselves highly attractive (Chu et al., 2011). For many people, their sexual personalities seem to result, in part, from their value as a potential mate, with somewhat different consequences for men and women.

3. Our Eyes, Voices, Lips, and Genitals Reveal Sexual Personalities. It used to be thought that our physical bodies had very little to do with our personalities. In 2011, researchers found several intriguing associations between our physical bodies and our sexual personalities. In one study, researchers found the larger the black ring in our eyes (the thin black slice that surrounds the colored area of the iris), the more people find us attractive (Peshek et al., 2011); a second study found the deeper men's voices, the more they are perceived to be unfaithful (O'Connor et al., 2011); a third study found the more prominent the middle section of a woman's upper lip (called the tubercle), the more likely she is to have orgasms (Brody et al., 2011); and finally a study found the longer the distance between a woman's clitoris and her urethral meatus (indicating high prenatal androgen exposure), the less likely she is to experience orgasms (Wallen et al., 2011). Our physical bodies seem to be made up of cues and clues to our past, present, and future sexual personalities.

2. Resisting Infidelity Depends on Sexual Personalities. Lots of studies have shown that our personality traits—like extraversion and impulsivity—are related to whether we cheat on our mates or stay faithful. In 2011, researchers found a feature of our personality called "executive control" is really important for sexual fidelity, especially in terms of our ability to resist flirting with attractive members of the opposite sex (Pronk et al., 2011). On the opposite side of the coin is the trait of avoidant attachment, as people who are romantically dismissing tend to pay more attention to attractive alternatives to their current mate and such people also stray more over time (DeWall et al., 2011). Finally, Mark et al. (2011) found that among women (but not men), being dissatisfied with one's relationship matters as much as our personality in predicting infidelity. Being able to stay focused, feel real intimacy, and chose a satisfying partner all seem to be keys to unlocking our most faithful sexual selves.