Final answer:
The incest taboo is present in every society but can vary widely; it generally prohibits sexual relations between close kin, but the definition of 'close kin' can differ. Practices like levirate and varying first-cousin marriage laws in the U.S. demonstrate these exceptions. Societal norms shape the scope and application of the incest taboo.
Step-by-step explanation:
The incest taboo is a universal cultural norm that prohibits sexual relations between certain family members, but there are exceptions and variations in how this taboo is applied across different societies. While the taboo typically includes parents and their offspring, in some cultures the taboo may vary when considering relatives of the father or mother, or may extend to more distant relations such as first cousins. For instance, first-cousin marriage laws in the United States differ state by state, and some societies may have norms like the levirate, where a man marries his late brother's widow, shaping their unique incest taboos. The role of sexual attitudes and practices in society is influenced by a number of factors including family, education, peers, media, religious beliefs, and the values upheld within the society.