Final answer:
Cross-cultural research demonstrates that there are no universal rules about sexual preferences in human societies. The variations in gender and sexuality are due to humans being highly variable and culturally diverse.
Step-by-step explanation:
Cross-cultural research demonstrates that there are no universal rules about sexual preferences in human societies, other than males and females are both required to reproduce. This is happening in part because humans are highly variable and culturally diverse in their expressions of gender and sexuality. Evidence from primate research, human biology, and archaeology suggests that significant behavioral differences between males and females are not biologically hardwired but are influenced by social and cultural factors.