Individual differences are unique characteristics that develop throughout an individual’s life and are formed based on genetic predisposition and lived experiences. These individual differences can modulate (inhibiting or favoring) the expression of behaviors, including sexual risk behaviors. Sexual risk behaviors are those that expose the individual to physical risck, such as involvement with sexually transmitted infections (STIs), and to social risk and vulnerability, such as early pregnancy. In our work, we present the theoretical concepts about natural selection and sexual selection, as well as the Theory of Parental Investment and Theory of Sexual Strategies; in addition, we detail the concepts of sexual risk behaviors and individual differences. Furthermore, we investigated individual differences and their relationship with risky sexual behavior, as well as variables related to individual characteristics, such as use of pre-exposure prophylaxis to HIV (PrEP) and non-mongamous tendency. Data collect was online, with 293 participants, who answered instruments of personality traits, impulsiveness, sexual sensation seeking, life history strategies and sociosexual orientation, and also a sociodemographic questionnaire with information on sexual risk behaviors. From the sociodemographic data related to sexual risk behaviors, the Sexual Risk Score was created, which represents the level of exposure to sexual risks of each participant, containing information on the number of sexual partners, condom use, substance use during the sexual act, use of PrEP etc. This score was used for data analysis through correlation tests. It was found that sex, sexual orientation and socioeconomic status did not correlate with sexual risks. Extroversion, narcissism and psychopathy personality traits, as well as sexual sensation seeking and unrestricted sociosexual orientation were positively correlated with sexual risks. In turn, neither impulsivity nor the life history strategy correlated with sexual risks. This work brings information about how sexual risk behaviors can have their expression increased due to individual differences, which may favor the increase in the number of individuals affected by sexually transmitted infections (STIs). This knowledge brings an important contribution to combating the spread of STIs, and can be used to prevent new infections from occurring.