Sexual Behavior human 74 Humans 73 sexual behavior 72 male 63 female 60 adult 59 Male 56 Female 54 Adult 49 psychology 39 adolescent 34 article 34 Adolescent 33 sexuality 32 young adult 32 Young Adult 31 major clinical study 30 Sexual Partners 27 HIV Infections 21 controlled study 21 Human immunodeficiency virus infection 20 Middle Aged 18 middle aged 18 questionnaire 17 human experiment 16 Homosexuality, Male 15 Human immunodeficiency virus 15 Surveys and Questionnaires 15 male homosexuality 15