Chapter 8 of Cultural Anthropology discusses the role that sex and gender play in the culture around you, including in the classroom, family, workplace, place of worship, and everywhere else. Gender refers to the cultural construction of sexual differences. Male and female are biological sexes that differ in their X and Y chromosomes. Culture takes that biological difference and associates it with certain activities, behavior, and ideas. Some cultures recognize more than two genders. Gender roles are the activities a culture assigns to each sex. Gender stratification describes an unequal distribution of resources between men and women. Sometimes, a distinction between women's domestic work and men's extra-domestic "productive" labor can reinforce a contrast between men as public and valuable and women as domestic and less valuable. Gender stratification varies with the economy, political system, rule of descent, and postmarital residence pattern. Matrilineal and bilateral societies tend to have less gender stratification than patrilineal-patrilocal societies do. Anthropological evidence casts some doubt on the idea that sexual orientation is fixed. To some extent at least, erotic expression is learned and malleable. Despite individual variation in sexual orientation within a society, culture always plays a role in molding individual sexual urges toward a collective norm. Sexual norms vary widely from culture to culture. Patriarchy describes a political system in which women have inferior social political status, including basic human rights. Although anthropologists know of no matriarchies, women in many societies do wield power and lead. Economic forces have contributed to recent changes in gender roles and stratification. In North America, female cash labor has increased, promoting greater economic and social autonomy of many women. But also increasing, globally, is the feminization of poverty, the rise in the percentages of female-