Heteronormativity is the body of lifestyle norms that hold that people fall into distinct and complementary genders (man and woman) with natural roles in life. It also holds that heterosexuality is the normal sexual orientation, and states that sexual and marital relations are most (or only) fitting between a man and a woman. Consequently, a "heteronormative" view is one that involves alignment of biological sex, sexuality, gender identity, and gender roles.
Read more about Heteronormativity: Origin of The Term, Discrimination, Relation To Marriage and The Nuclear Family, Homonormativity