1. Cultural concepts and values: In some cultural traditions, sex is regarded as a very private and sensitive topic, and discussing it may be considered inappropriate or disturbing.
2. Personal shame: Some parents may feel that their grasp of sexual knowledge is limited, or they may feel embarrassed or uncomfortable when talking about sex with their children.
3. Social pressure: Sometimes, there are some ideas or pressures in society that children's sex education is inappropriate or absurd, which makes some parents afraid of being accused or judged by others.
4. Belief and religious factors: Religious beliefs may have an impact on parents' attitudes. Some religious doctrines may think that sex education should be led by religious institutions or families, not schools or other external channels.
However, more and more people realize the importance of children's sex education in cultivating healthy physical and mental development and preventing sexual abuse. Therefore, advocates of modern education are trying to change this concept and advocate open and appropriate sex education. Sex education can help children understand their own bodies, determine healthy relationships and boundaries, and how to protect themselves and others.