Final answer:
Sex is not culturally constructed, while race, gender, kinship, and sexual norms are defined by social criteria and thus can vary across cultures.
Step-by-step explanation:
The sociocultural construction of race, gender, kinship, and sexual norms indicates that these categories are defined not by biological truths but by social criteria, which can vary widely across different cultures. Sex, however, is categorically distinct as it refers to the biological differences between male and female organisms, based on physiology and anatomy, even though some scholars challenge the objectivity of these categories. Thus, sex is not culturally constructed in the same way as the other options. Therefore, the answer to the student's question would be 'Sex' is not culturally constructed.