Final answer:
Heteronormativity is the societal assumption that heterosexuality is the only valid sexual orientation, privileging it over others, and possibly leading to systemic disadvantages for LGBTQ individuals. Heterosexism is a related concept that encompasses discriminatory attitudes and biases in favor of heterosexuality.
Step-by-step explanation:
Social institutions, practices, and norms that support an automatic assumption that other people are or should be heterosexual is called heteronormativity. This term refers to an ideology and a set of institutional practices that privilege heterosexuals and heterosexuality over other sexual orientations, leading to systemic disadvantages for those who do not conform to this norm. Heterosexism is a similar concept, depicting attitudes, bias, and discrimination favoring heterosexuality, akin to the ways in which racism and sexism create systemic disadvantages.
Despite increasing awareness and acceptance of diverse sexual orientations and identities, many societies remain heteronormative. This can result in LGBTQ individuals being treated as 'others' and can cause significant distress. For instance, policies like the Employee Non-Discrimination Act, which prohibits workplace discrimination based on sexual orientation, are relatively recent developments in the fight against such discrimination.
Anthropological research has illustrated that human sexuality is a flexible aspect of culture and that same-sex practices can be common, even in heteronormative societies. These practices sometimes exist alongside expectations for heterosexual marriage and family life, indicating the complexity and variability of human sexual behavior across different cultural contexts.