Considering the traditional concept of sex in China's official discourse and lack of social support system for sex education in China, burgeoning Internet knowledge community serves as an important forum for unprepared Chinese young parents to discuss and improve sex education. In this study, we conducted a structural topic modeling analysis of sex education discussions on Zhihu, the biggest online knowledge community in China. We found attention towards sex education are biased in China, where basic sexual terminologies are mentioned, but other important topics such as reproductive health, emotional attachment, and gender identity are insufficient or even absent, failing to fulfill the goal of Comprehensive Sexuality Education (CSE). This study paid special attention to gender differences in discussants, expected educators, and expected receivers of sex education. Findings show that boys are not considered as important sex education objects as girls, although many of them suffered from sexual assault and sexual diseases. They are always mentioned as roles that offend women rather than promoting or protecting themselves through sexual knowledge. Most discussants and expected educators of sex education are women, reflecting men's lack of attention to sex education issues as both individuals and fathers.
Keywords: health communication; online knowledge community; sex education; structural topic modeling.