We explored the balance of genetic and environmental factors on sexual dysfunctions during first intercourse experience in young men. Gender role conflict theory predicts that young males should show high levels of such dysfunctions coupled with mixed affective reactions. Three thousand one hundred eighty six male twins and their siblings (M = 26.17 years, SD = 4.77) completed items on erectile dysfunction (ED), premature ejaculation (PE), contextual factors, and affective reactions during first intercourse, as well as parental attitudes towards nudity and sexuality. Twin modeling revealed a significant genetic effects for PE, but not for ED. Experiences of sexual dysfunction and both negative and positive affects during first intercourse were common among the participants. More positive parental attitudes were associated with less dysfunction and more positive affect during first intercourse. Having the first sexual intercourse with an unknown partner and while strongly intoxicated were, together with group pressure and reluctance to engage in intercourse, related to more negative and less positive affects. Erectile dysfunction during the first intercourse was related to more negative and less positive affects.