Preferences for sexual arousal by overstated dominance and submission in sex is categorized as F65.5, sadomasochism, according to ICD, but this behaviour is called BDSM among the general public. The ground of these preferences could be ultimately biological. These preferences reflect behavioural strategy which enables to gain higher reproductive success. Men and women who were sexually aroused by a submissive partner had more male relatives than men and women with other preferences. Contrary to the women, the dominant men reported themselves as more attractive. Women who were aroused by a higher-ranking partner considered themselves more attractive. Sons of couples in which was hierarchical disparity had more siblings than sons of "equal" couples or couples with no hierarchical disparity. Daughters of hierarchically disparate couples had more brothers than daughters of "both dominant" partners. Concurrently, number and gender of offspring as well as self- reported attractiveness are likely to be criteria of the reproductive success in humans. It is also interesting that hierarchically disparate couples, without regard to gender of higher-ranking partner, reached higher reproductive success than "equal" couples. Individuals who preferred higher- or lower-ranking partner were also aroused by...